TOHOKU UNIVERSITY Researchers - Takeshi Nishimura

Details of the Researcher

Home

日本語 English

Takeshi Nishimura

Section

Graduate School of Science

Job title

Professor

Degree

博士（理学）（東北大学）
理学修士（東北大学）

researchmap

https://researchmap.jp/vnishi

J-GLOBAL ID

200901090098654663

Research History 3

1992/04 - 2000/03

東北大学大学院理学研究科　助手
2012/04 -

東北大学大学院理学研究科　教授
2000/04 -

Graduate School of Science, Tohoku University　Associate Professor

Education 3

Tohoku University　Graduate School, Division of Natural Science　Department of Geophysics, Doctoral Course

- 1992/03
Tohoku University　Graduate School, Division of Natural Science　Department of Geophysics (Master's Course)

- 1988/03
Tohoku University　Faculty of Science　天文及び地球物理学科第二

- 1986/03

Committee Memberships 19

日本地震学会　代議員

2024/04 - Present
Volcanological Society of Japan　President

2020/07 - 2022/06
日本火山学会　理事

2014/07 - 2022/06
日本地震学会　代議員

2009/04 - 2022/03
IAVCEI　Bulletin of Volcanology編集委員

2013/06 - 2019/05
日本火山学会編集委員会　桜島特集号編集委員

2011/01 - 2013/04
日本火山学会編集委員会　桜島特集号編集委員

2011/01 - 2013/04
日本火山学会・各賞選考委員会　委員

2010/07 - 2012/06
日本火山学会・各賞選考委員会　委員

2010/07 - 2012/06
日本火山学会　学会誌編集委員長

2006/07 - 2010/06
日本火山学会　学会誌編集委員長

2006/07 - 2010/06
日本火山学会　学会誌編集委員

2002/04 - 2006/06
日本火山学会　学会誌編集委員

2002/04 - 2006/06
日本地震学会　学会誌編集委員

2004/04 - 2006/03
日本地震学会　学会誌編集委員

2004/04 - 2006/03
日本地震学会　情報誌編集委員

1999/04 - 2001/03
日本地震学会　情報誌編集委員

1999/04 - 2001/03
日本地震学会　情報誌編集委員長

1998/04 - 1999/03
日本地震学会　情報誌編集委員長

1998/04 - 1999/03

Show all ︎Show first 5

Professional Memberships 4

日本災害情報学会
American Geophysical Union
日本火山学会
日本地震学会

Research Interests 7

Mantle
Crust
Fault
Magma
Eruption
Volcano
Earthquake

Research Areas 1

Natural sciences / Solid earth science /

Awards 2

日本地震学会論文賞

2008/05/27　日本地震学会　Temporal changes in seismic velocity of the crust around Iwate volcano, Japan, as inferred from analyses of repeated active seismic experiment data from 1998 to 2003
2006年度火山学会論文賞

2006/10　日本火山学会

Papers 159

Complex principal component analysis of volcanic earthquakes at Azuma volcano, Japan, recorded by a distributed acoustic sensing system (DAS) for the hypocenter determination Peer-reviewed

Takeshi Nishimura, Fumiya Morisaku, Kentaro Emoto, Hisashi Nakahara, Mare Yamamoto, Satoshi Miura

Journal of Volcanology and Geothermal Research　463　108343-108343　2025/07
Publisher: Elsevier BV
DOI： 10.1016/j.jvolgeores.2025.108343 　

ISSN： 0377-0273
Variability of ETAS parameters and their relationship with physical processes for earthquake forecasting in Africa Peer-reviewed

Thystere Matondo Bantidi, Takeshi Nishimura, Takeo Ishibe, Bogdan Enescu, Georges Mavonga Tuluka

Earth, Planets and Space　77　(1)　2025/03/10
Publisher: Springer Science and Business Media LLC
DOI： 10.1186/s40623-025-02151-7 　

eISSN： 1880-5981

More details Close

Abstract The epidemic-type aftershock sequence (ETAS) model is commonly used for seismic risk assessment and earthquake forecasting. It incorporates physically interpretable parameters that control the behavior of offsprings. Variability in these parameters suggests that earthquakes are driven by distinct mechanisms. Since these parameters vary with local geological factors and are not transferable across tectonic settings, region-specific calibration is essential. Currently, however, no ETAS parameter estimates exist for Africa, so seismic hazard assessments on the continent often rely on approximations rather than tailored approaches. To address this, we investigate ETAS parameters variability across Africa by dividing the continent into sub-regions and fitting the model to earthquakes in each subregion using the Davidon–Fletcher–Powell optimization algorithm. We then compare parameter estimates across sub-regions and examine potential correlations with physical properties of the Earth’s crust that are commonly thought to be the main driving factor in earthquake occurrence. Our results reveal complex regional variations in ETAS estimates. Parameters that describe productivity (α), temporal decay (c), and spatial distribution (d, γ) of aftershocks appear to be the most widely dispersed, probably due to missing events in the catalog caused by sparse seismic networks. Additionally, we observe correlations between certain parameters and geophysical properties of the crust, including a positive correlation between the parameter p, which represents the decay of aftershocks, and both heat flow and the compressional-to-shear-wave velocity ratio, and a negative correlation with Curie depth. An extreme value distribution analysis suggests a relatively high probability of a magnitude 7 or greater earthquake occurring in Northwest Africa and the western East African Rift System within the next decade, underscoring the need for measures that enhance public awareness and preparedness in these regions. Our results provide a preliminary set of ETAS parameters for Africa and can serve as a reference for implementing operational earthquake forecasting on the continent. Graphical Abstract
Volcanic tremor associated with successive gas emission activity at a boiling pool: Analyses of seismic array and visible image data recorded at Iwo-Yama in Kirishima Volcanic complex, Japan

Masato Hata, Takeshi Nishimura, Takeshi Matsushima, Tomofumi Kozono, Tsutomu Nagatsuma, Ken T. Murata, Kazutaka Kikuta, Dan Muramatsu, Hisashi Nakahara

Journal of Volcanology and Geothermal Research　455　108212-108212　2024/11
Publisher: Elsevier BV
DOI： 10.1016/j.jvolgeores.2024.108212 　

ISSN： 0377-0273
Modelling uncertainty in P-wave arrival-times retrieved from DAS data: case-studies from 15 fibre optic cables Peer-reviewed

E Bozzi, N Piana Agostinetti, A Fichtner, S Klaasen, A Ugalde, B Biondi, S Yuan, T Dahm, M Isken, P Paitz, F Walter, A F Baird, C Becerril, T Nishimura, J Shen, T Zhu, G Saccorotti

Geophysical Journal International　239　(3)　1928-1942　2024/10/07
Publisher: Oxford University Press (OUP)
DOI： 10.1093/gji/ggae364 　

ISSN： 0956-540X

eISSN： 1365-246X

More details Close

SUMMARY Distributed acoustic sensing (DAS) technology enables the detection of waves generated by seismic events, generally as uniaxial strain/strain rate time-series observed for dense, subsequent, portions of a Fibre Optic Cable (FOC). Despite the advantages in measurement density, data quality is often affected by uniaxial signal polarization, site effects and cable coupling, beyond the physical energy decay with distance. To better understand the relative importance of these factors for data inversion, we attempt a first modelling of noise patterns affecting DAS arrival times for a set of seismic events. The focus is on assessing the impact of noise statistics, together with the geometry of the problem, on epicentral location uncertainties. For this goal, we consider 15 ‘real-world’ cases of DAS arrays with different geometry, each associated with a seismic event of known location. We compute synthetic P-wave arrival times and contaminate them with four statistical distributions of the noise. We also estimate P-wave arrival times on real waveforms using a standard seismological picker. Eventually, these five data sets are inverted using a Markov chain Monte Carlo method, which offers the evaluation of the relative event location differences in terms of posterior probability density (PPD). Results highlight how cable geometry influences the shape, extent and directionality of the PPDs. However, synthetic tests demonstrate how noise assumptions on arrival times often have important effects on location uncertainties. Moreover, for half of the analysed case studies, the observed and synthetic locations are more similar when considering noise sources that are independent of the geometrical characteristics of the arrays. Thus, the results indicate that axial polarization, site conditions and cable coupling, beyond other intrinsic features (e.g. optical noise), are likely responsible for the complex distribution of DAS arrival times. Overall, the noise sensitivity of DAS suggests caution when applying geometry-only-based approaches for the a priori evaluation of novel monitoring systems.
Vulcanian eruptions at Sakurajima Volcano: geophysical data, numerical modelling, and petrological evidence

Takeshi Nishimura, Tomofumi Kozono, Akiko Matsumoto, Mitsuhiro Nakagawa, Masato Iguchi

Bulletin of Volcanology　86　(4)　2024/03/04
Publisher: Springer Science and Business Media LLC
DOI： 10.1007/s00445-024-01722-y 　

eISSN： 1432-0819

More details Close

Abstract We investigated the magma conduit system beneath three active craters that have repeatedly generated Vulcanian eruptions at Sakurajima Volcano, Japan, by analysing seismic, infrasound, and tilt data. The hypocentres of the earthquakes associated with the Vulcanian eruptions are distributed separately at shallow depths of approximately 0.5 km beneath the craters. Infrasound indicated that the swelling of the crater floor starts approximately 0.2 s after the occurrence of earthquakes and that the eruption starts about 0.3 to 0.5 s later. During an eruption, tilt vectors at a station approximately 2.7 km far from the active craters indicated a deflationary trend directed toward one of the three active craters. A 1-D conduit flow simulation indicated pressure build-up at a depth of 0.4–1.0 km beneath the crater, consistent with previously reported pressure sources during eruptions detected by geodesy. Volcanic lapilli emitted from the three craters have the same chemical composition; hence, Vulcanian eruptions of all three studied craters originate from a common magma source.
Complex spatial distribution of onset amplitude and waveform correlation: case studies from different DAS experiments Peer-reviewed

E. Bozzi, G. Saccorotti, N. Piana Agostinetti, C. Becerril, A. Fichtner, S. Klaasen, T. Nishimura, J. Shen, F. Walter, T. Zhu

Bulletin of Geophysics and Oceanography　65　271-290　2024
Time-lapse imaging of seismic scattering property and velocity in the northeastern Japan

Takashi Hirose, Qing-Yu Wang, Michel Campillo, Hisashi Nakahara, Ludovic Margerin, Eric Larose, Takeshi Nishimura

Earth and Planetary Science Letters　619　118321-118321　2023/10
Publisher: Elsevier BV
DOI： 10.1016/j.epsl.2023.118321 　

ISSN： 0012-821X
Anisotropic seismic velocity variations in response to different orientations of tidal deformations

Tomoya Takano, Takeshi Nishimura, Hisashi Nakahara

Geophysical Journal International　235　(3)　2716-2726　2023/09/18
Publisher: Oxford University Press (OUP)
DOI： 10.1093/gji/ggad386 　

ISSN： 0956-540X

eISSN： 1365-246X

More details Close

SUMMARY Microcracks or micropores in rocks cause the elastic moduli to change with the applied strain owing to the nonlinear elasticity of the geomaterial, which causes temporal changes in the seismic wave velocity. Thus, variations in seismic wave velocity can be used as a proxy for understanding the strain or stress variations in the crust, which are crucial for figuring out the dynamics of the fault zones and volcanic domains. According to the theory of nonlinear elasticity, the second- and third-order elastic constants and strain tensors contribute to the strain derivative of seismic wave velocity changes. Although laboratory experiments have estimated third-order elastic constants for rock samples, the in situ values of those constants for the crust are difficult to obtain. In this study, seismic velocity changes were investigated in different directions of tidal deformations to provide constraints on the third-order elastic constants in the shallow crust by applying a seismic interferometry method to ambient noise records. We observed that negative velocity changes were of larger magnitude in the station-pair direction parallel to the tidal strain’s direction. Nonlinear elasticity in shallow crust may cause anisotropic velocity variations in response to tidal deformations. Our results highlight the use of velocity change measurements in different directions of tidal strain to constrain nonlinear elastic parameters on a field scale.
Fine Structure of Tremor Migrations Beneath the Kii Peninsula, Southwest Japan, Extracted With a Space‐Time Hough Transform

Kodai Sagae, Hisashi Nakahara, Takeshi Nishimura, Kazutoshi Imanishi

Journal of Geophysical Research: Solid Earth　128　(6)　2023/05/27
Publisher: American Geophysical Union (AGU)
DOI： 10.1029/2022jb026248 　

ISSN： 2169-9313

eISSN： 2169-9356
Spatio-temporal clustering of successive earthquakes as inferred from analyses of global CMT and NIED F-net catalogs

Thystere Matondo Bantidi, Takeshi Nishimura

Earth, Planets and Space　74　(1)　2022/07/27
Publisher: Springer Science and Business Media LLC
DOI： 10.1186/s40623-022-01677-4 　

eISSN： 1880-5981

More details Close

Abstract Investigation of the characteristic behavior of successive earthquakes that closely occur in space and time is important to understand the generation mechanism of earthquakes and useful to assess a triggered earthquake, especially around the area, where a first large earthquake took place. Here, we analyzed the Global Centroid Moment Tensor catalog from 1976 to 2016 for shallow earthquakes with a moment magnitude, $${M}_{w}$$, of at least 5.5, and the F-net catalog, Japan, for $$4\le {M}_{w}<5.5$$, to clarify the spatio-temporal characteristics of the successive earthquakes. We first sorted all of the earthquakes in time and removed the aftershocks that occurred in and around the faults of earthquakes with $${M}_{w}$$ larger than the target magnitude range we investigated. Then, we selected source events from the beginning and searched for earthquakes that occurred within a horizontal distance (D) and a lapsed time ($${T}_{a}$$) from the source event to group them in clusters. Then, the source event was selected from the catalog in order, and the same procedure was repeated. We counted the number of clusters, each of which consisted of successive earthquakes, for different D and $${T}_{a}.$$ To examine whether successive earthquakes were explained by random occurrences, we compared the results with simulations in which earthquakes occurred randomly in time but at the same locations matching the centroids in the real data. The comparison showed that the number of clusters for the simulation rapidly increased with D and merged with that for real data at a short distance, which is defined here as the triggering distance. We find that triggering distance is proportional to about 1/5 to 1/4 of the seismic moment $${(M}_{0})$$ of the source event, and exponentially decreases with increasing $${T}_{a}$$. Relating the derived empirical scaling relations between $${M}_{0}$$ and triggering distance from the equations in the ETAS model, we show that the observed exponents of 1/5 to 1/4 were well predicted from the estimated ETAS parameters in various regions around the world. These consistencies first show that successive occurrence of earthquakes is well explained by the ETAS model. Graphical abstract
Classification of volcanic tremors and earthquakes based on seismic correlation: application at Sakurajima volcano, Japan

Theodorus Permana, Takeshi Nishimura, Hisashi Nakahara, Nikolai Shapiro

GEOPHYSICAL JOURNAL INTERNATIONAL　229　(2)　1077-1097　2022/01

DOI： 10.1093/gji/ggab517 　

ISSN： 0956-540X

eISSN： 1365-246X
Source location of volcanic earthquakes and subsurface characterization using fiber-optic cable and distributed acoustic sensing system

Takeshi Nishimura, Kentaro Emoto, Hisashi Nakahara, Satoshi Miura, Mare Yamamoto, Shunsuke Sugimura, Ayumu Ishikawa, Tsunehisa Kimura

Scientific Reports　11　(1)　2021/12

DOI： 10.1038/s41598-021-85621-8 　

ISSN： 2045-2322

eISSN： 2045-2322
Ground deformation reveals the scale-invariant conduit dynamics driving explosive basaltic eruptions

M. Ripepe, G. Lacanna, M. Pistolesi, M. C. Silengo, A. Aiuppa, M. Laiolo, F. Massimetti, L. Innocenti, M. Della Schiava, M. Bitetto, F. P. La Monica, T. Nishimura, M. Rosi, D. Mangione, A. Ricciardi, R. Genco, D. Coppola, E. Marchetti, D. Delle Donne

Nature Communications　12　(1)　2021/12
Publisher: Springer Science and Business Media LLC
DOI： 10.1038/s41467-021-21722-2 　

eISSN： 2041-1723

More details Close

<title>Abstract</title>The mild activity of basaltic volcanoes is punctuated by violent explosive eruptions that occur without obvious precursors. Modelling the source processes of these sudden blasts is challenging. Here, we use two decades of ground deformation (tilt) records from Stromboli volcano to shed light, with unprecedented detail, on the short-term (minute-scale) conduit processes that drive such violent volcanic eruptions. We find that explosive eruptions, with source parameters spanning seven orders of magnitude, all share a common pre-blast ground inflation trend. We explain this exponential inflation using a model in which pressure build-up is caused by the rapid expansion of volatile-rich magma rising from depth into a shallow (<400 m) resident magma conduit. We show that the duration and amplitude of this inflation trend scales with the eruption magnitude, indicating that the explosive dynamics obey the same (scale-invariant) conduit process. This scale-invariance of pre-explosion ground deformation may usher in a new era of short-term eruption forecasting.
Scattering strength at active volcanoes in Japan as inferred from the peak ratio analysis of teleseismic P waves Peer-reviewed

Gugi Ganefianto, Hisashi Nakahara, Takeshi Nishimura

Earth, Planets and Space　73　207　2021/11

DOI： 10.1186/s40623-021-01541x 　
Extending the formulation of the spatial autocorrelation (SPAC) method to strain, rotation and tilt

Hisashi Nakahara, Kentaro Emoto, Takeshi Nishimura

GEOPHYSICAL JOURNAL INTERNATIONAL　227　(1)　287-302　2021/10

DOI： 10.1093/gji/ggab217 　

ISSN： 0956-540X

eISSN： 1365-246X
Introduction of Special Series on “Volcanology Course for Next Generation Researchers”

NISHIMURA Takeshi, ISHIBASHI Hidemi, MORI Toshiya, JIBIKI Yasuhito, NAKAMICHI Haruhisa, SAITO Takeshi, SHIMANO Taketo, YOSHIMURA Shumpei, MIYABUCHI Yasuo

BULLETIN OF THE VOLCANOLOGICAL SOCIETY OF JAPAN　66　(3)　133-134　2021/09/30
Publisher: The Volcanological Society of Japan
DOI： 10.18940/kazan.66.3_133 　

ISSN： 0453-4360

eISSN： 2189-7182
Volcanic eruptions are triggered in static dilatational strain fields generated by large earthquakes. Peer-reviewed

Takeshi Nishimura

Scientific Reports　11　17325　2021/08

DOI： 10.1038/s41598-021-96756-z 　
High resolution location of deep low-frequency tremors beneath the Kii Peninsula, Nankai subduction zone, Japan, using data from a dense seismic array

Kodai Sagae, Hisashi Nakahara, Takeshi Nishimura, Kazutoshi Imanishi

Geophysical Journal International　225　(2)　775-788　2021/02/15
Publisher: Oxford University Press (OUP)
DOI： 10.1093/gji/ggab004 　

ISSN： 0956-540X

eISSN： 1365-246X

More details Close

<title>SUMMARY</title> This study performs detection and location of deep low-frequency tremors beneath the Kii Peninsula, Nankai subduction zone, Japan, using data from a dense seismic array. We set a quantitative threshold for the tremor detection based on the Gaussian distribution of waveform coherence among stations to distinguish between tremor signal and noise. Then, we estimated slownesses and arrival azimuths by applying the Multiple Signal Classification method and performed hypocentre determination by backprojection onto the plate interface. During the analysed period of 2 yrs from July 2012 to July 2014, we detected 25155 tremor events which are approximately 2.2 times more than those in the AIST-tremor catalogue based on the conventional envelope correlation method ( 11475 events). This improvement is due to the detection of even weak amplitude tremors owing to the array analysis scheme, which uses recorded waveform’s phase information. Our high-resolution tremor catalogue leads to the following findings of the tremor activity in the Kii Peninsula. A few tremor episodes show continuous updip migration in the initial stage. The updip migration speed depends on whether the tremor migrates in the along-strike direction after the updip migration: approximately 1.0 km hr –1 for tremors that develop into the along-strike migration, and approximately 0.5 km hr–1 for those that do not. Estimated radiated energies are found to increase gradually with propagation into the updip direction. These findings suggest the depth dependence of the frictional strength on the plate interface. Furthermore, we noticed that accumulated radiated energies are positively correlated with the updip migration speed, and this relationship implies that fluid migration might play a role in the updip migration.
Electric field disturbances in 2020 observed nearby Sakurajima volcano, Japan

Y. Nakashima,, Nishimura T., Aoyama H., Iguchi M., Kanda W., Ohminato T.

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2021　163-163　2021
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2021.0_163 　

ISSN： 2433-5320

eISSN： 2189-7190
Locating Spatial Changes of Seismic Scattering Property by Sparse Modeling of Seismic Ambient Noise Cross‐Correlation Functions: Application to the 2008 Iwate‐Miyagi Nairiku ( M w 6.9), Japan, Earthquake Peer-reviewed

Takashi Hirose, Hisashi Nakahara, Takeshi Nishimura, Michel Campillo

Journal of Geophysical Research: Solid Earth　125　(6)　2020/06
Publisher: American Geophysical Union (AGU)
DOI： 10.1029/2019jb019307 　

ISSN： 2169-9313

eISSN： 2169-9356
Reliability evaluation of volcanic tremor source location determination using cross-correlation functions Peer-reviewed

Theodorus Permana, Takeshi Nishimura, Hisashi Nakahara, Eisuke Fujita, Hideki Ueda

GEOPHYSICAL JOURNAL INTERNATIONAL　220　(2)　1300-1315　2020/02

DOI： 10.1093/gji/ggz523 　

ISSN： 0956-540X

eISSN： 1365-246X
Capture of eruption column used by GPS: the Sakurajima eruption on August 18, 2013

Asakura Yukako, Nishimura Takeshi, Ohta Yusaku, Kano Masayuki, Iguchi Masato

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2020　40-40　2020
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2020.0_40 　

ISSN： 2433-5320

eISSN： 2189-7190
Noise-based passive ballistic wave seismic monitoring on an active volcano Peer-reviewed

Tomoya Takano, Florent Brenguier, Michel Campillo, Aline Peltier, Takeshi Nishimura

Geophysical Journal International　220　(1)　501-507　2020/01/01
Publisher: Oxford University Press (OUP)
DOI： 10.1093/gji/ggz466 　

ISSN： 0956-540X

eISSN： 1365-246X

More details Close

<title>SUMMARY</title> Monitoring temporal changes of volcanic interiors is important to understand magma, fluid pressurization and transport leading to eruptions. Noise-based passive seismic monitoring using coda wave interferometry is a powerful tool to detect and monitor very slight changes in the mechanical properties of volcanic edifices. However, the complexity of coda waves limits our ability to properly image localized changes in seismic properties within volcanic edifices. In this work, we apply a novel passive ballistic wave seismic monitoring approach to examine the active Piton de la Fournaise volcano (La Réunion island). Using noise correlations between two distant dense seismic arrays, we find a 2.4 per cent velocity increase and −0.6 per cent velocity decrease of Rayleigh waves at frequency bands of 0.5–1 and 1–3 Hz, respectively. We also observe a −2.2 per cent velocity decrease of refracted P waves at 550 m depth at the 6–12 Hz band. We interpret the polarity differences of seismic velocity changes at different frequency bands and for different wave types as being due to strain change complexity at depth associated with subtle pressurization of the shallow magma reservoir. Our results show that velocity changes measured using ballistic waves provide complementary information to interpret temporal changes of the seismic properties within volcanic edifices.
Gas flux cyclic regime at an open vent magmatic column inferred from seismic and acoustic records Peer-reviewed

Gen Kondo, Hiroshi Aoyama, Takeshi Nishimura, Maurizio Ripepe, Giorgio Lacanna, Riccardo Genco, Ryohei Kawaguchi, Taishi Yamada, Takahiro Miwa, Eisuke Fujita

Scientific Reports　9　(1)　2019/12
Publisher: Springer Science and Business Media LLC
DOI： 10.1038/s41598-019-42033-z 　

eISSN： 2045-2322
Spectral ratio analyses of explosion earthquakes at Sakurajima Volcano, Japan Peer-reviewed

Mohammad Hasib, Takeshi Nishimura, Hisashi Nakahara

JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH　381　302-311　2019/09

DOI： 10.1016/j.jvolgeores.2019.05.005 　

ISSN： 0377-0273

eISSN： 1872-6097
A Passive Estimation Method of Scattering and Intrinsic Absorption Parameters From Envelopes of Seismic Ambient Noise Cross-Correlation Functions Peer-reviewed

Takashi Hirose, Hisashi Nakahara, Takeshi Nishimura

GEOPHYSICAL RESEARCH LETTERS　46　(7)　3634-3642　2019/04

DOI： 10.1029/2018GL080553 　

ISSN： 0094-8276

eISSN： 1944-8007
Sensitivity of Seismic Velocity Changes to the Tidal Strain at Different Lapse Times: Data Analyses of a Small Seismic Array at Izu-Oshima Volcano Peer-reviewed

Tomoya Takano, Takeshi Nishimura, Hisashi Nakahara, Hideki Ueda, Eisuke Fujita

JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH　124　(3)　3011-3023　2019/03

DOI： 10.1029/2018JB016235 　

ISSN： 2169-9313

eISSN： 2169-9356
噴火発生頻度の時空間的特徴―グローバルデータベースの解析― Peer-reviewed

西村太志

火山　64　53-61　2019
Interaction between moderate earthquakes and volcanic eruptions: analyses of global data catalog Peer-reviewed

Takeshi Nishimura

Geophy. Res. Lett　45　2018/08

DOI： 10.1029/2018GL079060 　
サブミリ測地解析による火山活動モニタリング

三浦哲, 山本希, 市來雅啓, 出町知嗣, 立花憲司, 西村太志

地殻活動研究委員会報告書（平成29年度）　40　81-86　2018/03
Azimuth estimations from a small aperture infrasonic array: test observations at Stromboli volcano, Italy Peer-reviewed

Yamakawa K, Ichihara,M, Ishii, K, Aoyama, H, Nishimura, T, Ripepe, M

Geophysical Research Letters　45　(17)　8931-8938　2018
Publisher: American Geophysical Union (AGU)
DOI： 10.1029/2018GL07885 　

ISSN： 0094-8276
Triggering of volcanic eruptions by large earthquakes Peer-reviewed

Takeshi Nishimura

Geophysical Research Letters　44　(15)　7750-7756　2017/08/16
Publisher: Blackwell Publishing Ltd
DOI： 10.1002/2017GL074579 　

ISSN： 1944-8007 0094-8276
Seismic velocity changes concentrated at the shallow structure as inferred from correlation analyses of ambient noise during volcano deformation at Izu-Oshima, Japan Peer-reviewed

Tomoya Takano, Takeshi Nishimura, Hisashi Nakahara

JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH　122　(8)　6721-6736　2017/08

DOI： 10.1002/2017JB014340 　

ISSN： 2169-9313

eISSN： 2169-9356
Combined use of repeated active shots and ambient noise to detect temporal changes in seismic velocity: application to Sakurajima volcano, Japan Peer-reviewed

Takashi Hirose, Hisashi Nakahara, Takeshi Nishimura

EARTH PLANETS AND SPACE　69　2017/03

DOI： 10.1186/s40623-017-0613-7 　

ISSN： 1880-5981
Seismic velocity changes of P and S waves associated with the 2011 Tohoku-Oki earthquake (Mw9.0) as inferred from analyses of repeating earthquakes Peer-reviewed

Karim Pacheco, Takeshi Nishimura, Hisashi Nakahara

Geophysical Journal International　209　517-533　2017/02/02
Volcanic eruption volume flux estimations from very long period infrasound signals Peer-reviewed

Taishi Yamada, Hiroshi Aoyama, Takeshi Nishimura, Masato Iguchi, Muhamad Hendrasto

GEOPHYSICAL RESEARCH LETTERS　44　(1)　143-151　2017/01

DOI： 10.1002/2016GL071047 　

ISSN： 0094-8276

eISSN： 1944-8007
Initial phases of explosion earthquakes accompanying Vulcanian eruptions at Lokon-Empung volcano, Indonesia Peer-reviewed

Taishi Yamada, Hiroshi Aoyama, Takeshi Nishimura, Hiroshi Yakiwara, Haruhisa Nakamichi, Jun Oikawa, Masato Iguchi, Muhamad Hendrasto, Yasa Suparman

JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH　327　310-321　2016/11

DOI： 10.1016/j.jvolgeores.2016.08.011 　

ISSN： 0377-0273

eISSN： 1872-6097
Tracking dynamics of magma migration in open-conduit systems Peer-reviewed

Sebastien Valade, Giorgio Lacanna, Diego Coppola, Marco Laiolo, Marco Pistolesi, Dario Delle Donne, Riccardo Genco, Emanuele Marchetti, Giacomo Ulivieri, Carmine Allocca, Corrado Cigolini, Takeshi Nishimura, Pasquale Poggi, Maurizio Ripepe

BULLETIN OF VOLCANOLOGY　78　(11)　2016/11

DOI： 10.1007/s00445-016-1072-x 　

ISSN： 0258-8900

eISSN： 1432-0819
Magnitude-frequency distribution of volcanic explosion earthquakes Peer-reviewed

Takeshi Nishimura, Masato Iguchi, Mohammad Hendrasto, Hiroshi Aoyama, Taishi Yamada, Maurizio Ripepe, Riccardo Genco

EARTH PLANETS AND SPACE　68　2016/07

DOI： 10.1186/s40623-016-0505-2 　

ISSN： 1880-5981
Estimating S-Wave Attenuation in Sediments by Deconvolution Analysis of KiK-net Borehole Seismograms Peer-reviewed

Rintaro Fukushima, Hisashi Nakahara, Takeshi Nishimura

BULLETIN OF THE SEISMOLOGICAL SOCIETY OF AMERICA　106　(2)　552-559　2016/04

DOI： 10.1785/0120150059 　

ISSN： 0037-1106

eISSN： 1943-3573
Woodpecker seismicity before the flank effusive eruption at Stromboli

Aoyama Hiroshi, Yamada Taishi, Nishimura Takeshi, Kawaguchi Ryohei, Miwa Takahiro, Fujita Eisuke, Ripepe Maurizio, Genco Riccardo

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2016　164-164　2016
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2016.0_164 　
Relative hypocenter determination of eruption earthquakes at Stromboli volcano based on a temporary observation in June 2015 (2)

Sugimura Shunsuke, Nishimura Takeshi, Aoyama Hiroshi, Yamada Taishi, Fujita Eisuke, Miwa Takahiro, Kawaguchi Ryohei, Ripepe Maurizio, Genco Riccardo, Valade Sebastien

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2016　165-165　2016
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2016.0_165 　
Seismic velocity changes and crustal deformation at Izuoshima - Analyses of JMA data -

Takano Tomoya, Nishimura Takeshi, Nakahara Hisashi

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2016　39-39　2016
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2016.0_39 　
Tilt motion prior to an explosion at Stromboli volcano, Italy (3)

Kawaguchi R., Nishimura T., Aoyama H., Yamada T., Miwa T., Fujita E., Ripepe M., Genco R., Lacanna G.

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2016　166-166　2016
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2016.0_166 　
Large earthquakes and volcanic eruptions

Nishimura Takeshi

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2016　103-103　2016
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2016.0_103 　
Detection of spatio-temporal changes of seismic scattering properties associated with the dike intrusion on 15 August 2015 at Sakurajima volcano based on seismic interferometry

Hirose Takashi, Nakahara Hisashi, Nishimura Takeshi

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2016　106-106　2016
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2016.0_106 　
Source characteristics of explosion earthquakes at Sakurajima volcano using spectral ratio method

Hasib Mohammad, Nishimura Takeshi, Nakahara Hisashi

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2016　18-18　2016
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2016.0_18 　
Numerical investigation of temporal changes in volcanic deformation caused by a gas slug ascent in the conduit Peer-reviewed

Ryohei Kawaguchi, Takeshi Nishimura

JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH　302　1-10　2015/09

DOI： 10.1016/j.jvolgeores.2015.06.002 　

ISSN： 0377-0273

eISSN： 1872-6097
P40 Relative hypocenter determination of eruption earthquakes using deconvolution : Application to Stromboli volcano (2)

Sugimura Shunsuke, Nishimura Takeshi, Aoyama Hiroshi, Yamada Taishi, Fujita Eishuke, Kawaguchi Ryohei, Miwa Takahiro, Ripepe Maurizio, Genco Riccardo

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2015　138-138　2015
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2015.0_138 　
P33 Tilt motion prior to an explosion at Stromboli volcano, Italy (2)

Kawaguchi R., Nishimura T., Aoyama H., Yamada T., Miwa T., Fujita E., Ripepe M., Genco R., Lacanna G

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2015　131-131　2015
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2015.0_131 　
B1-09 Volcanic earthquake activity and eruption : recent examples in Japan

Nishimura Takeshi, Takagi Akimichi

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2015　55-55　2015
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2015.0_55 　
B1-18 Near crater observation and recent activity of Tokachi-dake volcano

Aoyama H., Hashimoto T., Nishimura T., Ichiki M., Koyama T., Okada K., Tanaka R., Yamada T., Ounaga R., Mishima W.

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2015　64-64　2015
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2015.0_64 　
In situ observations of velocity changes in response to tidal deformation from analysis of the high-frequency ambient wavefield Peer-reviewed

G. Hillers, L. Retailleau, M. Campillo, A. Inbal, J. -P. Ampuero, T. Nishimura

JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH　120　(1)　210-225　2015/01

DOI： 10.1002/2014JB011318 　

ISSN： 2169-9313

eISSN： 2169-9356
Characterization of the luminance and shape of ash particles at Sakurajima volcano, Japan, using CCD camera images Peer-reviewed

Takahiro Miwa, Taketo Shimano, Takeshi Nishimura

BULLETIN OF VOLCANOLOGY　77　(1)　2015/01

DOI： 10.1007/s00445-014-0886-7 　

ISSN： 0258-8900

eISSN： 1432-0819
Seismic velocity changes caused by the Earth tide: Ambient noise correlation analyses of small-array data Peer-reviewed

Tomoya Takano, Takeshi Nishimura, Hisashi Nakahara, Yusaku Ohta, Sachiko Tanaka

GEOPHYSICAL RESEARCH LETTERS　41　(17)　6131-6136　2014/09

DOI： 10.1002/2014GL060690 　

ISSN： 0094-8276

eISSN： 1944-8007
Development of an automatic volcanic ash sampling apparatus for active volcanoes Peer-reviewed

Taketo Shimano, Takeshi Nishimura, Nobuyuki Chiga, Yoshinobu Shibasaki, Masato Iguchi, Daisuke Miki, Akihiko Yokoo

BULLETIN OF VOLCANOLOGY　75　(12)　2013/12

DOI： 10.1007/s00445-013-0773-7 　

ISSN： 0258-8900

eISSN： 1432-0819
Mechanism of small vulcanian eruptions at Suwanosejima volcano, Japan, as inferred from precursor inflations and tremor signals Peer-reviewed

Takeshi Nishimura, Masato Iguchi, Hiroshi Yakiwara, Jun Oikawa, Ryohei Kawaguchi, Hiroshi Aoyama, Haruhisa Nakamichi, Yusaku Ohta, Takeshi Tameguri

BULLETIN OF VOLCANOLOGY　75　(12)　2013/12

DOI： 10.1007/s00445-013-0779-1 　

ISSN： 0258-8900

eISSN： 1432-0819
Envelope synthesis of a cylindrical outgoing wavelet in layered random elastic media based on the markov approximation Peer-reviewed

Kentaro Emoto, Haruo Sato, Takeshi Nishimura

Geophysical Journal International　194　(2)　899-910　2013/07

DOI： 10.1093/gji/ggt125 　

ISSN： 0956-540X 1365-246X
Structure of Northeastern Sakurajima, South Kyushu, Japan, Revealed by Seismic Reflection Survey(＜Special Section＞Sakurajima Special Issue) Peer-reviewed

TSUTSUI Tomoki, WATANABE Atsushi, YAGI Naofumi, IGUCHI Masato, TAMEGURI Takeshi, MIKADA Hitoshi, ONISHI Kyosuke, MIYAMACHI Hiroki, NISHIMURA Takeshi, MORITA Yuichi

BULLETIN OF THE VOLCANOLOGICAL SOCIETY OF JAPAN　58　(1)　239-250　2013
Publisher: The Volcanological Society of Japan
DOI： 10.18940/kazan.58.1_239 　

ISSN： 0453-4360

More details Close

Seismic reflection structure in the northeast part of Sakurajima Volcano is discussed down to ca. 11 km with three profiles. Data acquisition was conducted along intersecting two lines with 221 stations and eight shot points. The two lines covered the northeastern portion of the volcano. One of the lines was spread along NNW to SSE direction in the east foot, and another line was oriented east to west in the northern flank of the volcano. Data processing were made through the conventional procedure of the reflection seismology, and depth migrated sections were obtained. Four continuous reflection horizons appear in the profiles. One of the reflection horizons around 5.4 km depth disappears in the northeast portion of the coverage area. The interruption of the horizon suggests existence of magma or magma supply path beneath it. The inferred magma supply path locates to the west of that previously presented.
Volcano inflation prior to an eruption: Numerical simulations based on a 1-D magma flow model in an open conduit Peer-reviewed

Ryohei Kawaguchi, Takeshi Nishimura, Haruo Sato

Earth, Planets and Space　65　(12)　1477-1489　2013
Publisher: Springer Berlin
DOI： 10.5047/eps.2013.05.005 　

ISSN： 1880-5981 1343-8832
Spatio-temporal changes in seismic velocity associated with the 2000 activity of Miyakejima volcano as inferred from cross-correlation analyses of ambient noise Peer-reviewed

Titi Anggono, Takeshi Nishimura, Haruo Sato, Hideki Ueda, Motoo Ukawa

JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH　247　93-107　2012/12

DOI： 10.1016/j.jvolgeores.2012.08.001 　

ISSN： 0377-0273

eISSN： 1872-6097
Inflations prior to Vulcanian eruptions and gas bursts detected by tilt observations at Semeru Volcano, Indonesia Peer-reviewed

Takeshi Nishimura, Masato Iguchi, Ryohei Kawaguchi, Surono, Muhamad Hendrasto, Umar Rosadi

BULLETIN OF VOLCANOLOGY　74　(4)　903-911　2012/05

DOI： 10.1007/s00445-012-0579-z 　

ISSN： 0258-8900
Seismic Array Observation Close to the Active Crater at Suwanose-jima Volcano, Southwest Japan for the Period from October to November 2010

NAKAMICHI HARUHISA, AOYAMA HIROSHI, NISHIMURA TAKESHI, YAKIWARA HIROSHI, OTA YUSAKU, YOKOO AKIHIKO, IGUCHI MASATO

京都大学防災研究所年報(CD-ROM)　(56)　227-235　2012
Publisher:
ISSN： 0386-412X

More details Close

We conducted a small-aperture seismic array observation at Suwanose-jima volcano for the period from 1 October to 18 November 2010. The seismic array consists of 13 elements of short-period seismometers and 5 data loggers. We perform array analysis for continuous seismic records observed during this period to investigate the wave-field properties of several episodes of volcanic tremors and 30 explosion earthquakes. Averages of the slowness values and back azimuths of volcanic tremors are estimated to be 0.8-1.4 s/km and 0°-40°, respectively. This suggests that the tremor wave consists of body and surface waves that propagate from the active crater. The array analyses and particle motions of explosion earthquakes indicate that the initial parts of the waveforms of explosion earthquakes are S waves that come from the direction of the active crater. The slowness values of the S waves of the explosion earthquakes are 0.3-0.5 s/km. Variation of the slowness value reflects the depth change of the explosion sources.
Synthesis and applicable condition of vector wave envelopes in layered random elastic media with anisotropic autocorrelation function based on the Markov approximation Peer-reviewed

Kentaro Emoto, Haruo Sato, Takeshi Nishimura

GEOPHYSICAL JOURNAL INTERNATIONAL　188　(1)　325-335　2012/01

DOI： 10.1111/j.1365-246X.2011.05264.x 　

ISSN： 0956-540X
Methods for eruption prediction and hazard evaluation at Indonesian volcanoes Peer-reviewed

Masato Iguchi, Surono, Takeshi Nishimura, Muhamad Hendrasto, Umar Rosadi, Takahiro Ohkura, Hetty Triastuty, Ahmad Basuki, Agoes Loeqman, Sukir Maryanto, Kazuhiro Ishihara, Mitsuhiro Yoshimoto, Setsuya Nakada, Natsumi Hokanishi

Journal of Disaster Research　7　(1)　26-36　2012/01

DOI： 10.20965/jdr.2012.p0026 　

ISSN： 1881-2473

eISSN： 1883-8030
Heterogeneity of the Japanese islands as inferred from transverse component analyses of teleseismic P-waves observed at a seismic station network, Hi-net Peer-reviewed

Takeshi Nishimura

EARTH PLANETS AND SPACE　64　(11)　E25-E28　2012

DOI： 10.5047/eps.2012.10.001 　

ISSN： 1343-8832
Envelope synthesis of short-period seismograms in 3-D random media for a point shear dislocation source based on the forward scattering approximation: Application to small strike-slip earthquakes in southwestern Japan Peer-reviewed

Kaoru Sawazaki, Haruo Sato, Takeshi Nishimura

JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH　116　doi:10.1029/2010JB008182　2011/08

DOI： 10.1029/2010JB008182 　

ISSN： 2169-9313

eISSN： 2169-9356
Seismicity and magma supply rate of the 1998 failed eruption at Iwate volcano, Japan (vol 73, pg 133, 2011) Peer-reviewed

T. Nishimura, S. Ueki

BULLETIN OF VOLCANOLOGY　73　(3)　367-367　2011/04

DOI： 10.1007/s00445-010-0438-8 　

ISSN： 0258-8900
Seismicity and magma supply rate of the 1998 failed eruption at Iwate volcano, Japan Peer-reviewed

Takeshi Nishimura, Sadato Ueki

BULLETIN OF VOLCANOLOGY　73　(2)　133-142　2011/03

DOI： 10.1007/s00445-010-0438-8 　

ISSN： 0258-8900

eISSN： 1432-0819
P35 Effusion cycle of a simple analog experiment of geyser

Yoshida Satoshi, Nishimura Takeshi, Sato Haruo

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2011　147-147　2011
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2011.0_147 　
B3-08 Deflation Process Associated with Explosive Eruption at Showa Crater of Sakurajima

Iguchi Masato, Nishimura Takeshi

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2011　105-105　2011
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2011.0_105 　
Direct observation of rupture propagation during the 2011 off the Pacific coast of Tohoku Earthquake (M-w 9.0) using a small seismic array Peer-reviewed

Hisashi Nakahara, Haruo Sato, Takeshi Nishimura, Hiroyuki Fujiwara

EARTH PLANETS AND SPACE　63　(7)　589-594　2011

DOI： 10.5047/eps.2011.06.002 　

ISSN： 1343-8832
Synthesis of vector wave envelopes on the free surface of a random medium for the vertical incidence of a plane wavelet based on the Markov approximation Peer-reviewed

Kentaro Emoto, Haruo Sato, Takeshi Nishimura

Journal of Geophysical Research: Solid Earth　115　(8)　doi:10.1029/2009JB006955　2010/08/01
Publisher: Blackwell Publishing Ltd
DOI： 10.1029/2009JB006955 　

ISSN： 2169-9356 2169-9313
P06 Effect of topography on volcano deformation caused by magma in an open conduit by Finite Element Method

Kitamura You, Nishimura Takeshi, Sato Haruo

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2010　98-98　2010
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2010.0_98 　
2-A08 Volcano Inflation prior to Gas Explosion Events at Semeru Volcano, Indonesia

Nishimura Takeshi, Iguchi Masato, Kawaguchi Ryohei, Surono, Hendrasto Muhamad, Rosadi Umar

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2010　26-26　2010
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2010.0_26 　
Ground deformation caused by magma ascent in an open conduit Peer-reviewed

Takeshi Nishimura

Journal of Volcanology and Geothermal Research　187　(3-4)　178-192　2009/11/10

DOI： 10.1016/j.jvolgeores.2009.09.001 　

ISSN： 0377-0273
Ground deformation caused by magma ascent in an open conduit Peer-reviewed

Takeshi Nishimura

JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH　187　(3-4)　178-192　2009/11

DOI： 10.1016/j.jvolgeores.2009.09.001 　

ISSN： 0377-0273
Tomographic inversion of the peak delay times to reveal random velocity fluctuations in the lithosphere: method and application to northeastern Japan Peer-reviewed

Tsutomu Takahashi, Haruo Sato, Takeshi Nishimura, Kazushige Obara

GEOPHYSICAL JOURNAL INTERNATIONAL　178　(3)　1437-1455　2009/09

DOI： 10.1111/j.1365-246X.2009.04227.x 　

ISSN： 0956-540X
Time-Lapse Changes of Seismic Velocity in the Shallow Ground Caused by Strong Ground Motion Shock of the 2000 Western-Tottori Earthquake, Japan, as Revealed from Coda Deconvolution Analysis Invited Peer-reviewed

Kaoru Sawazaki, Haruo Sato, Hisashi Nakahara, Takeshi Nishimura

BULLETIN OF THE SEISMOLOGICAL SOCIETY OF AMERICA　99　(1)　352-366　2009/02

DOI： 10.1785/0120080058 　

ISSN： 0037-1106

eISSN： 1943-3573
B12 Volcano deformation due to magma ascent in an open conduit : Calculation using a 1-D conduit magma flow model

Kawaguchi Ryohei, Nishimura Takeshi, Sato Haruo

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2009　62-62　2009
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2009.0_62 　
P10 Estimation of Gas Bubble Growth in Magma from Volcano Deformation Data Prior to Eruption

Nishimura Takeshi

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2009　110-110　2009
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2009.0_110 　
Volcanic tremor during eruptions: Temporal characteristics, scaling and constraints on conduit size and processes Peer-reviewed

Stephen R. McNutt, Takeshi Nishimura

JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH　178　(1)　10-18　2008/11

DOI： 10.1016/j.jvolgeores.2008.03.010 　

ISSN： 0377-0273
Recursive formula for the peak delay time with travel distance in von Karman type non-uniform random media on the basis of the Markov approximation Peer-reviewed

Tsutomu Takahashi, Haruo Sato, Takeshi Nishimura

GEOPHYSICAL JOURNAL INTERNATIONAL　173　(2)　534-545　2008/05

DOI： 10.1111/j.1365-246X.2008.03739.x 　

ISSN： 0956-540X
B07 Temporal Changes of Seismic Velocity of Shallow Structure Associated With the 2000 Miyakejima Volcano Activity

Anggono Titi, Nishimura Takeshi, Sato Haruo, Ueda Hideki, Ukawa Motoo

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2008　59-59　2008
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2008.0_59 　
B03 Seismic activity at Iwate volcano after the 1998 intrusive event

Ueki S., Ohta Y., Zhao D., Hirahara S., Nakayama T., Nishimura T., Tanaka S.

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2008　55-55　2008
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2008.0_55 　
Synthesis of coda wave envelopes in randomly inhomogeneous elastic media in a half-space: single scattering model including Rayleigh waves Invited Peer-reviewed

Takuto Maeda, Haruo Sato, Takeshi Nishimura

GEOPHYSICAL JOURNAL INTERNATIONAL　172　(1)　130-154　2008/01

DOI： 10.1111/j.1365-246X.2007.03603.x 　

ISSN： 0956-540X
Evaluation of strength of heterogeneity in the lithosphere from peak amplitude analyses of teleseismic short-period vector P waves Invited Peer-reviewed

Mungiya Kubanza, Takeshi Nishimura, Haruo Sato

GEOPHYSICAL JOURNAL INTERNATIONAL　171　(1)　390-398　2007/10

DOI： 10.1111/j.1365-246X.2007.03544.x 　

ISSN： 0956-540X
Strong inhomogeneity beneath Quaternary volcanoes revealed from the peak delay analysis of S-wave seismograms of microearthquakes in northeastern Japan Invited Peer-reviewed

Tsutomu Takahashi, Haruo Sato, Takeshi Nishimura, Kazushige Obara

GEOPHYSICAL JOURNAL INTERNATIONAL　168　(1)　90-99　2007/01

DOI： 10.1111/j.1365-246X.2006.03197.x 　

ISSN： 0956-540X
Ground deformation due to magma ascent with and without degassing Invited Peer-reviewed

Takeshi Nishimura

GEOPHYSICAL RESEARCH LETTERS　33　(23)　doi:10.1029/2006GL028101　2006/12

DOI： 10.1029/2006GL028101 　

ISSN： 0094-8276
Temporal change in site response caused by earthquake strong motion as revealed from coda spectral ratio measurement Peer-reviewed

Kaoru Sawazaki, Haruo Sato, Hisashi Nakahara, Takeshi Nishimura

GEOPHYSICAL RESEARCH LETTERS　33　(21)　doi:10.1029/2006GL027938　2006/11

DOI： 10.1029/2006GL027938 　

ISSN： 0094-8276
Bubble growth processes in magma surrounded by an elastic medium Peer-reviewed

Youichi Shimomura, Takeshi Nishimura, Haruo Sato

JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH　155　(3-4)　307-322　2006/07

DOI： 10.1016/j.jvolgeores.2006.04.003 　

ISSN： 0377-0273
B27 Volcanic explosivity and ground deformation of volcanic edifice(THE VOLCANOLOGICAL SOCIETY OF JAPAN 2006 FALL MEETING)

Nishimura Takeshi

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2006　83-83　2006
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2006.0_83 　
Investigation of the Onikobe geyser, NE Japan, by observing the ground tilt and flow parameters Peer-reviewed

Takeshi Nishimura, Mie Ichihara, Sadato Ueki

EARTH PLANETS AND SPACE　58　(12)　E21-E24　2006

DOI： 10.1186/BF03351967 　

ISSN： 1343-8832
Spatial variation of lithospheric heterogeneity on the globe as revealed from transverse amplitudes of short-period teleseismic P-waves Peer-reviewed

Mungiya Kubanza, Takeshi Nishimura, Haruo Sato

EARTH PLANETS AND SPACE　58　(12)　E45-E48　2006

DOI： 10.1186/BF03352618 　

ISSN： 1343-8832
Strong ground motions recorded by a near-source seismographic array during the 16 August 2005 Miyagi-Ken-Oki, JAPAN, earthquake (Mw 7.2) Peer-reviewed

Hisashi Nakahara, Kaoru Sawazaki, Nobumasa Takagi, Takeshi Nishimura, Haruo Sato, Hiroyuki Fujiwara

EARTH PLANETS AND SPACE　58　(12)　1555-1559　2006

DOI： 10.1186/BF03352660 　

ISSN： 1343-8832
Temporal changes in seismic velocity of the crust around Iwate volcano, Japan, as inferred from analyses of repeated active seismic experiment data from 1998 to 2003 Peer-reviewed

T Nishimura, S Tanaka, T Yamawaki, H Yamamoto, T Sano, M Sato, H Nakahara, N Uchida, S Hori, H Sato

EARTH PLANETS AND SPACE　57　(6)　491-505　2005

DOI： 10.1186/BF03352583 　

ISSN： 1343-8832
Application of single force model to the volcanic explosion earthquakes observed at Asama volcano in 2004 Peer-reviewed

Takeshi Nishimura, Higashi Uchida

Bulletin of the Volcanological Society of Japan　50　(5)　387-391　2005

DOI： 10.18940/kazan.50.5_387 　
Three-dimensional P-wave velocity structure of Bandai volcano in northeastern Japan inferred from active seismic survey Peer-reviewed

Teruo Yamawaki, Satoru Tanaka, Sadato Ueki, Hiroyuki Hamaguchi, Haruhisa Nakamichi, Takeshi Nishimura, Jun Oikawa, Tomoki Tsutsui, Kiyoshi Nishi, Hiroshi Shimizu, Sosuke Yamaguchi, Hiroki Miyamachi, Hitoshi Yamasato, Yutaka Hayashi

Journal of Volcanology and Geothermal Research　138　(3-4)　267-282　2004/12/15

DOI： 10.1016/j.jvolgeores.2004.07.010 　

ISSN： 0377-0273
Temporal change of seismic structure around Iwate volcano inferred from waveform correlation analysis of similar earthquakes Peer-reviewed

T Yamawaki, T Nishimura, H Hamaguchi

GEOPHYSICAL RESEARCH LETTERS　31　(24)　2004/12

DOI： 10.1029/2004GL021103 　

ISSN： 0094-8276

eISSN： 1944-8007
Pressure recovery in magma due to bubble growth Peer-reviewed

T Nishimura

GEOPHYSICAL RESEARCH LETTERS　31　(12)　doi:10.1029/2004GRL019810　2004/06

DOI： 10.1029/2004GL019810 　

ISSN： 0094-8276
B35 Bubble growth and pressure change in ascending magma : Effects of surrounding elastic medium

Shimomura Youichi, Nishimura Takeshi, Sato Haruo

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2004　99-99　2004
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2004.0_99 　
P19 Regularity and variability of Onikobe geyser

Ichihara Mie, Nishimura Takeshi, Goto Akio, Taniguchi Hiromitsu

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2004　129-129　2004
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2004.0_129 　
Moho and Philippine Sea plate structure beneath central Honshu Island, Japan, from teleseismic receiver functions Peer-reviewed

Kazuo Yoshimoto, Hiroatsu Fujisawa, Tomomi Okada, Norihito Umino, Akira Hasegawa, Kazushige Obara, Katsuhiko Shiomi, Hiroaki Tsukahara, Shigeru Okamoto, Taku Kawanaka, Hiroshi Sato, Takeshi Nishimura, Haruo Sato, Masakazu Ohtake

Earth, Planets and Space　56　(12)　1271-1277　2004
Publisher: Springer Berlin
DOI： 10.1186/BF03353350 　

ISSN： 1880-5981 1343-8832

eISSN： 1880-5981
Source mechanisms of deep and intermediate-depth low-frequency earthquakes beneath Iwate volcano, northeastern Japan Peer-reviewed

H Nakamichi, H Hamaguchi, S Tanaka, S Ueki, T Nishimura, A Hasegawa

GEOPHYSICAL JOURNAL INTERNATIONAL　154　(3)　811-828　2003/09

DOI： 10.1046/j.1365-246X.2003.01991.x 　

ISSN： 0956-540X

eISSN： 1365-246X
A numerical simulation of magma motion, crustal deformation, and seismic radiation associated with volcanic eruptions Peer-reviewed

T Nishimura, B Chouet

GEOPHYSICAL JOURNAL INTERNATIONAL　153　(3)　699-718　2003/06

DOI： 10.1046/j.1365-246X.2003.01936.x 　

ISSN： 0956-540X
Correction to "Spatial distribution of lateral heterogeneity in the upper mantle around the western Pacific region as inferred from analysis of transverse components of teleseismic P-coda" Peer-reviewed

Nishimura T, Yoshimoto K, Ohtaki T, Kanjo K, Purwana I

Geophysical Research Letters　30　(16)　9-1　2003
Pressurization associated with magma intrusion

Nishimura Takeshi

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2003　23-23　2003
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2003.0_23 　
Broadband seismic signals associated with the 2000 volcanic unrest of Mount Bandai, northeastern Japan Peer-reviewed

Takeshi Nishimura, Sadato Ueki, Teruo Yamawaki, Satoru Tanaka, Hironori Hashino, Minemori Sato, Haruhisa Nakamichi, Hiroyuki Hamaguchi

Journal of Volcanology and Geothermal Research　119　(1-4)　51-59　2003/01/01

DOI： 10.1016/S0377-0273(02)00305-0 　

ISSN： 0377-0273
Spatial distribution of lateral heterogeneity in the upper mantle around the western Pacific region as inferred from analysis of transverse components of teleseismic P-coda Peer-reviewed

T Nishimura, K Yoshimoto, T Ohtaki, K Kanjo, Purwana, I

GEOPHYSICAL RESEARCH LETTERS　29　(23)　10.1029/2002GL015606　2002/12

DOI： 10.1029/2002GL015606 　

ISSN： 0094-8276
Three-dimensional P-wave velocity structure of Iwate volcano, Japan from active seismic survey Peer-reviewed

S. Tanaka, H. Hamaguchi, T. Nishimura, T. Yamawaki, S. Ueki, H. Nakamichi, T. Tsutsui, H. Miyamachi, N. Matsuwo, J. Oikawa, T. Ohminato, K. Miyaoka, S. Onizawa, T. Mori, K. Aizawa

Geophysical Research Letters　29　(10)　2002/05/15

DOI： 10.1029/2002gl014983 　

ISSN： 0094-8276
A Numerical Study on Relations between Volcanic Eruptions, Magma Reservoir and Conduit

Nishimura Takeshi

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2002　62-62　2002
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2002.2.0_62 　
Source mechanism of very long period seismic events observed at Mount Bandai

Hashino Hironori, Nishimura Takeshi, Hamaguchi Hiroyuki

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2002　70-70　2002
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2002.2.0_70 　
Video image analysis of the eruptions on Stromboli Volcano

Goto Akio, Minato Akihiko, Ichihara Mie, Nishimura Takeshi, Fujita Eisuke

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2002　190-190　2002
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2002.2.0_190 　
1998Seismic Exploration, ASO98, in AsoVolcano

Sudo Yasuaki, Tsutsui Tomoki, Ono Hiroyasu

Bulletin of the Earthquake Research Institute, University of Tokyo　77　(4)　303-336　2002
Publisher: The University of Tokyo
ISSN： 0040-8972

More details Close

A seismic exploration, ASO98, was conducted in Aso Volcano in central Kyushu, Japan. The purpose of this exploration was both to obtain the detailed seismic structures beneath the central cones and to detect the kinematic character of volcanic tremors of Aso Volcano. Six shot points with chemical explosions and a temporary network with 296 seismic stations were deployed over the central cones in a range of 10 km east-west by 9 km north-south. All explosions were completed on 26 November, 1998, and seismic records were successfully acquired at each of 290 stations. This paper reports on the details of ASO98, such as examples of acquired seismic traces for shots, locations of stations and shots, Final first arrival times, amplitude distributions, and examples of records acquired of volcanic tremors. These data are expected to provide much knowledge about volcanic seismology and about Aso Volcano. Further analyses will be described in forthcoming papers.
Spatial distribution of high-frequency energy radiation on the fault of the 1995 Hyogo-ken Nanbu, Japan, earthquake (Mw6.9) on the basis of the seismogram envelope inversion Peer-reviewed

Nakahara, H, T. Nishimura, H. Sato, M. Ohtake, S. Kinoshita, H. Hamaguchi

Bull. Seismo. Soc. Am.　89　22-35　2002
Temopral change of seismi-wave velocity associated with the 1998 northern Iwate Prefecture, Japan Earthquake Peer-reviewed

内田直希, 西村太志, 吉本和生, 中原恒, 佐藤春夫, 大竹政和, 田中聡, 浜口博之T

Bull Seismol Soc Jpn　55　(2)　193-206　2002
Publisher:
DOI： 10.4294/zisin1948.55.2_193 　

ISSN： 0037-1114
Heterogeneous Structure of the Upper Mantle Beneath Active Volcanoes as Inferred From Seismic Scattering Waves

Nishimura T., Yoshimoto K., Kanjo K., Ohtaki T., PURWANA Ibunu

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2001　58-58　2001
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2001.2.0_58 　
Source process of very long period seismic events associated with the 1998 activity of Iwate Volcano, northeastern Japan Peer-reviewed

T Nishimura, H Nakamichi, S Tanaka, M Sato, T Kobayashi, S Ueki, H Hamaguchi, M Ohtake, H Sato

JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH　105　(B8)　19135-19147　2000/08

DOI： 10.1029/2000JB900155 　

ISSN： 2169-9313

eISSN： 2169-9356
Temporal changes of the crustal structure associated with the M6.1 earthquake on September 3, 1998, and the volcanic activity of Mount Iwate, Japan Peer-reviewed

T Nishimura, N Uchida, H Sato, M Ohtake, S Tanaka, H Hamaguchi

GEOPHYSICAL RESEARCH LETTERS　27　(2)　269-272　2000/01

DOI： 10.1029/1999GL005439 　

ISSN： 0094-8276
爆発的噴火の力学過程 Peer-reviewed

NISHIMURA Takeshi

月刊地球　22　324-332　2000
岩手火山1998年の長周期地震活動 Peer-reviewed

NISHIMURA Takeshi

月刊地球　21　(5)　280-284　1999/05
Publisher:
ISSN： 0387-3498
Spatial distribution of high-frequency energy radiation on the fault of the 1995 Hyogo-Ken Nanbu, Japan, earthquake (M-W 6.9) on the basis of the seismogram envelope inversion Peer-reviewed

H Nakahara, H Sato, M Ohtake, T Nishimura

BULLETIN OF THE SEISMOLOGICAL SOCIETY OF AMERICA　89　(1)　22-35　1999/02

ISSN： 0037-1106
1998年9月3日岩手県内陸北部地震（M6.1）と岩手火山活動に伴う地殻構造の時間変化

西村太志, 内田直希, 佐藤春夫, 大竹政和, 田中聡, 浜口博之

月刊地球　号外No.27　161-166　1999
Source mechanisms of volcanic explosion earthquakes: single force and implosive sources Peer-reviewed

T Nishimura

JOURNAL OF VOLCANOLOGY AND GEOTHERMAL RESEARCH　86　(1-4)　97-106　1998/11

DOI： 10.1016/S0377-0273(98)00088-2 　

ISSN： 0377-0273
Moment tensor inversion based on strong-motion data recorded around Mount Iwate

Nakahara Hisashi, Nishimura Takeshi, Kinoshita Shigeo, Sato Haruo, Ohtake Masakazu, Miura Satoshi, Ueki Sadato, Hamaguchi Hiroyuki

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　1998　7-7　1998
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.1998.2.0_7 　
Seismogram envelope inversion for the spatial distribution of high-frequency energy radiation from the earthquake fault: Application to the 1994 far east off Sanriku earthquake, Japan Peer-reviewed

H Nakahara, T Nishimura, H Sato, M Ohtake

JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH　103　(B1)　855-867　1998/01

DOI： 10.1029/97JB02676 　

ISSN： 2169-9313

eISSN： 2169-9356
Heterogeneous structure around the Jemez volcanic field, New Mexico, USA, as inferred from the envelope inversion of active-experiment seismic data Peer-reviewed

T Nishimura, M Fehler, WS Baldridge, P Roberts, L Steck

GEOPHYSICAL JOURNAL INTERNATIONAL　131　(3)　667-681　1997/12

DOI： 10.1111/j.1365-246X.1997.tb06605.x 　

ISSN： 0956-540X
Horizontal layered structure with heterogeneity beneath continents and island arcs from particle orbits of long-period P waves Peer-reviewed

T Nishimura

GEOPHYSICAL JOURNAL INTERNATIONAL　127　(3)　773-782　1996/12

DOI： 10.1111/j.1365-246X.1996.tb04056.x 　

ISSN： 0956-540X
Source process of the 1994 far east off Sanriku Earthquake, Japan, as inferred from a broad-band seismogram Peer-reviewed

Nishimura, T, H. Nakahara, H. Sato, M. Ohtake

Tohoku Geophysical Journal　34　(4)　121-134　1996/10
Temporal variation of mechanism of eruptive activity as inferred from eruption tremor

Nishimura Takeshi, McNutt Stephen R.

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　1996　54-54　1996
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.1996.2.0_54 　
Heterogeneous Structure around the Valles Caldera, New Mexico, USA, as Inferred from Envelope Inversion of Seismic Data from Man-made Explosion

Nishimura Takeshi, Michael Fehler

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　1996　190-190　1996
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.1996.2.0_190 　
Seismic Velocity Structure Beneath Kirishima Volcanoes with Differential Analysis of Explosion Experiment Peer-reviewed

TUTUI Tomoki, NISHIMURA Yuichi, KAGIYAMA Tsuneomi, MIKADA Hitoshi, MORITA Yuichi, MATSUSHIMA Takeshi, IGUCHI Masato, OIKAWA Jun, YAMAOKA Koshun, KUMAGAI Hiroyuki, MIYAMACHI Hiroki, WATANABE Toru, NISHIMURA Takeshi, TAKAGI Akimichi, YAMAMOTO Keigo, HAMAGUCHI Hiroyuki, OKADA Hiromu, MAEKAWA Tokumitsu, OSHIMA Hiromitsu, UEKI Sadato, HASHIMOTO Keiichi, NIDA Koichi, SHIGEHARA Satoshi, NAKAMICHI Haruhisa, SHIOMI Kastuhiko, NAKAHARA Hisashi, AOKI Shigeki, AOCHI Hideo, IDA Yoshiaki, WATANABE Hidefumi, ONIZAWA Shin-ya, OSADA Noboru, GYODA Noriya, TSUJI Hiroshi, YAMAGUCHI Masaru, MASUTANI Fumio, NISHIDOMI Ippei, INOUE Tomohiro, ITO Wataru, OKUDA Takashi, MIYAJIMA Rikio, SHIBATA Motoei, KITO Tadashi, TSURUGA Kayoko, MAEDA Mitoshi, SHIMIZU Hiroshi, MATSUO Norimichi, UMAKOSHI Kodo, UCHIDA Kazunari, OKUMURA Takashi, SHIBATA Manabu, SUDO Yasuaki, YOSHIKAWA Shin, YAMADA Toshihiro, MORI Takehiko, MATSUMOTO Yoshihiro, TAKAYAMA Testuro, HENDRASTO Muhamad, HIRANO Shuichiro, YAKIWARA Hiroshi, UENO Hiroshi, ISHIHARA Kazuhiko, MORI Hirokazu, HIRABAYASHI Jun-ichi, OBA Takeshi, NOGAMI Kenji, MORI Toshiya, SATO Masaki, TOMONAGA Sadao

BULLETIN OF THE VOLCANOLOGICAL SOCIETY OF JAPAN　41　(5)　227-241　1996
Publisher: The Volcanological Society of Japan
DOI： 10.18940/kazan.41.5_227 　

ISSN： 0453-4360

More details Close

Seismic velocity structures beneath Kirishima volcanoes are estimated down to 3 km from the surface with the differential analysis of refraction from the explosion experiment. Three layers are interpreted in the central and northern part of the volcanoes and two layers are interpreted in the southern part of the volcanoes. Through the northern and middle part of the volcanoes, the first layer whose velocity is 2.1 km/s is almost constant thickness of 0.5 km. The second layer whose velocity is 3.6 km/s is 0.5 km thickness at the end of the northern volcanoes and thicken northwestward into 3 km thickness. The third layer whose velocity is 5.8 km/s is estimated. In the southern part of the volcanoes, all velocities are higher than those of the northern or middle part. Several features appear in the profiles; a discontinuity around Takachiho-gawara in the south part of the volcanoes, north-westward declination of the third layer as a basement, and no low velocity zone beneath recent active craters down to 3 km depth. These results are consistent with the results of Magnetotelluric survey.
SOURCE PARAMETERS OF THE VOLCANIC-ERUPTION EARTHQUAKES AT MOUNT-TOKACHI, HOKKAIDO, JAPAN, AND A MAGMA ASCENDING MODEL Peer-reviewed

T NISHIMURA

JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH　100　(B7)　12465-12473　1995/07

DOI： 10.1029/95JB00867 　

ISSN： 2169-9313

eISSN： 2169-9356
SOURCE MECHANISMS OF VOLCANIC TREMOR AND LOW-FREQUENCY EARTHQUAKES ASSOCIATED WITH THE 1988-89 ERUPTIVE ACTIVITY OF MT-TOKACHI, HOKKAIDO, JAPAN Peer-reviewed

T NISHIMURA, H HAMAGUCHI, S UEKI

GEOPHYSICAL JOURNAL INTERNATIONAL　121　(2)　444-458　1995/05

DOI： 10.1111/j.1365-246X.1995.tb05725.x 　

ISSN： 0956-540X

eISSN： 1365-246X
Observation of tremor at Kamoshika fumarole in Mt Zao

Nishimura Takeshi, Aoki Shigeki

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　1995　59-59　1995
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.1995.2.0_59 　
Estimation of Ishimoto-Iida'sm-value for seismic sources included in volcanic tremor Peer-reviewed

NISHIMURA Takeshi

Bulletin of the Volcanological Society of Japan　40　(1)　53-57　1995
Publisher: Volcanological Society of Japan
DOI： 10.18940/kazan.40.1_53 　

ISSN： 0453-4360
Source Parameters of Eruption Earthquakes and a Magma Ascending Model

Nishimura Takeshi

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　1994　114-114　1994
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.1994.2.0_114 　
m-value of Sources in Volcanic Tremor

Nishimura Takeshi

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　1994　47-47　1994
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.1994.2.0_47 　
GPSを内蔵した小型データロガーの開発 Peer-reviewed

NISHIMURA Takeshi

地震2　46　(2)　79-83　1994

DOI： 10.4294/zisin1948.47.1_79 　
SCALING LAW OF VOLCANIC EXPLOSION EARTHQUAKE Peer-reviewed

T NISHIMURA, H HAMAGUCHI

GEOPHYSICAL RESEARCH LETTERS　20　(22)　2479-2482　1993/11

ISSN： 0094-8276
諏訪之瀬島火山における空中電位の観測

西村太志, 浜口博之

第2回諏訪之瀬島火山の集中観測-1989年-　95-100　1993/10
Standard Clock for Seismic Observations Using GPS Receiver Board Peer-reviewed

NISHIMURA Takeshi

地震2　46,67-74　(2)　67-74　1993

DOI： 10.4294/zisin1948.46.2_67 　

ISSN： 0037-1114
PROCESS OF THE 1977 NYIRAGONGO ERUPTION INFERRED FROM THE ANALYSIS OF LONG-PERIOD EARTHQUAKES AND VOLCANIC TREMORS Peer-reviewed

H HAMAGUCHI, T NISHIMURA, N ZANA

TECTONOPHYSICS　209　(1-4)　241-254　1992/08

ISSN： 0040-1951
Scaling Law of Explosive Eruption

Nishimura T., Hamaguchi H.

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　1992　81-81　1992
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.1992.2.0_81 　
ニアムラギラ火山の側噴火に伴う微動の発生過程 Peer-reviewed

NISHIMURA Takeshi

月刊地球　14　762-767　1992
ニイラゴンゴ火山の噴火と溶岩湖の消滅 Peer-reviewed

NISHIMURA Takeshi

月刊地球　14　768-767　1992
1998年9月3日岩手県内陸北部地震(M6.1)と岩手火山活動に伴う地殻構造の時間変化 Peer-reviewed

NISHIMURA Takeshi

月刊地球　27　161-166　1992
A Felt Earthquake (M4) near Volcano Nyiragongo on Novermber 20,1990

Nishimura T., Morita Y., Hamaguchi H., Tanaka K., Wafula M., Lukaya M., Zana N.

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　1991　65-65　1991
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.1991.1.0_65 　
Source Mechanism of the Volcanic Tremor Accompnied by 1989 Eruptive Activity of Mt. Tokachi

Nishimura T., Ueki S., Hamaguchi H.

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　1991　107-107　1991
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.1991.2.0_107 　
Precise Hypocenter after the Eruption of Teishi Knoll, 1989. Peer-reviewed

NISHIMURA Takeshi

月刊地球　13　(2)　74-78　1991
Seismic Activity Accompanying the 1989 off-Ito Submarine Eruption : (3) Comparison with the 1930 Ito Earthquake Swarms

Ueki S., Hamaguchi H., Morita Y., Nishimura T.

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　1990　53-53　1990
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.1990.2.0_53 　
Seismic Array Observation Associated with the Explosive Eruptions of Suwanose-jima Volcano

Nishimura Y., Nishi K., Sawada M., Hamaguchi H., Nishimura T.

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　1990　12-12　1990
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.1990.2.0_12 　
Caribration of natural frequency and damping constant of L-4C short-period seismometer Peer-reviewed

NISHIMURA Takeshi

地震 2　43　(2)　p279-282　1990
Publisher:
DOI： 10.4294/zisin1948.43.2_279 　

ISSN： 0037-1114
A15 1989 年伊東沖海底噴火後の微動活動

西村太志, 植木貞人, 森田裕一, 浜口博之

日本火山学会講演予稿集　1989　16-16　1989
Publisher: 特定非営利活動法人日本火山学会
DOI： 10.18940/vsj.1989.2.0_16 　
B21 磐梯山の微小地震活動

浜口博之, 植木貞人, 西村太志, 梅津功, 橋本恵一

日本火山学会講演予稿集　1989　99-99　1989
Publisher: 特定非営利活動法人日本火山学会
DOI： 10.18940/vsj.1989.2.0_99 　
A14 1989 年伊東沖海底噴火直後の微小地震の精密震源分布

植木貞人, 森田裕一, 堀内茂木, 西村太志, 田中聡, 橋本恵一, 浜口博之

日本火山学会講演予稿集　1989　14-15　1989
Publisher: 特定非営利活動法人日本火山学会
DOI： 10.18940/vsj.1989.2.0_14 　
32 十勝岳噴火(1988-1989 年)の地球物理学的研究 : その 2 国立大学共同観測

宮町宏樹, 西村裕一, 森済, 前川徳光, 鈴木敦生, 岡田弘, 植木貞人, 西村太志, 清水洋, 大見士朗, 山科健一郎, 渡辺秀文, 須藤靖明, 石原和弘, 笠原稔, 岡山宗夫

日本火山学会講演予稿集　1989　33-33　1989
Publisher: 特定非営利活動法人日本火山学会
DOI： 10.18940/vsj.1989.1.0_33 　
35 十勝岳火山噴火活動に伴う地震波の小規模アレイによる観測

西村太志, 植木貞人, 宮町宏樹, 西村裕一

日本火山学会講演予稿集　1989　36-36　1989
Publisher: 特定非営利活動法人日本火山学会
DOI： 10.18940/vsj.1989.1.0_36 　
4 1977 年ニイラゴンゴ火山噴火過程

西村太志, 浜口博之, ZANA N.

日本火山学会講演予稿集　1988　4-4　1988
Publisher: 特定非営利活動法人日本火山学会
DOI： 10.18940/vsj.1988.2.0_4

Show all ︎Show first 5

Misc. 66

Small seismic array analysis of gas emission activity at Kirishima Iwo-Yama volcano

Hata Masato, Nishimura Takeshi, Matsushima Takeshi, Muramatsu Dan, Nagatsuma Tsutomu, Murata Takeshi, Kozono Tomofumi, Tanabe Harutou

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2023　88-88　2023
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2023.0_88 　

ISSN： 2433-5320

eISSN： 2189-7190
Hypocenter determination of volcanic earthquakes at Azuma volcano: analyses of seismic array data of fiber optics and DAS system

西村太志, 江本賢太郎, 中原恒, 三浦哲, 山本希, 杉村俊輔, 植田尚大, 石川歩, 木村恒久

日本地球惑星科学連合大会予稿集(Web)　2020　2020
Analysis of dense records of the DAS observation using fiber optic cable in the urban area

江本賢太郎, 中原恒, 西村太志, 山本希, 寒河江皓大, GANEFIANTO Gugi, 矢武克啓

日本地震学会秋季大会講演予稿集(CD-ROM)　2020　2020
Estimation of Site Amplification of Azuma volcano: Analyses of Seismic Signals Recorded by Fiber Optic Cable and DAS

西村太志, 江本賢太郎, 中原恒, 三浦哲, 山本希, 杉村俊輔, 石川歩, 木村恒久

日本地震学会秋季大会講演予稿集(CD-ROM)　2020　2020
サブミリ測地解析による火山活動モニタリング (地殻活動研究委員会報告書(平成29年度))

三浦哲, 山本希, 市來雅啓, 出町知嗣, 立花憲司, 西村太志

東濃地震科学研究所報告　(40)　81-85　2018/03
Publisher: 地震予知総合研究振興会東濃地震科学研究所
Magnitude-frequency distribution of volcanic explosion earthquakes (vol 68, 125, 2016)

Takeshi Nishimura, Masato Iguchi, Mohammad Hendrasto, Hiroshi Aoyama, Taishi Yamada, Maurizio Ripepe, Riccardo Genco

EARTH PLANETS AND SPACE　69　2017/10

DOI： 10.1186/s40623-017-0728-x 　

ISSN： 1880-5981
室内実験及びStromboli空振観測のMUSIC法による小規模アレイ解析

山河和也, 石井杏佳, 市原美恵, 青山裕, 西村太志

日本火山学会講演予稿集　2017/09

DOI： 10.18940/vsj.2017.0_189 　
蔵王山総合観測における地震観測網の展開

平原聡, 三浦哲, 岡田知己, 中山貴史, 太田雄策, 立花憲司, 出町知嗣, 市來雅啓, 海田俊輝, 山本希, 西村太志, 大園真子

東京大学地震研究所技術研究報告　(20)　2015

ISSN： 1342-6486
吾妻山周辺の地殻変動

三浦哲, 山本希, 市來雅啓, 西村太志, 太田雄策, 出町知嗣

日本地球惑星科学連合大会予稿集(Web)　2015　2015
B1-06 Tilt motion prior to an explosion at Stromboli volcano, Italy

Kawaguchi R., Nishimura T., Aoyama H., Yamada T., Fujita E., Miwa T., Genco Riccardo, Lacanna Giorgio, Ripepe Maurizio

Programme and abstracts the Volcanological Society of Japan　2014　60-60　2014/11/02
Publisher: Volcanological Society of Japan
UP-21 Preliminary cross-correlation analyses of ambient noise before and after the 2014 eruption of Ontake volcano

Nishimura Takeshi

Programme and abstracts the Volcanological Society of Japan　2014　U24　2014/11/02
Publisher: Volcanological Society of Japan
P2-17 Tilt observation near to Okama crater at Mt. Zaozan

Nishimura Takeshi

Programme and abstracts the Volcanological Society of Japan　2014　169-169　2014/11/02
Publisher: Volcanological Society of Japan
Characteristics of magnitude-frequency distributions of eruption earthquakes associated with Vulcanian and Strombolian explosions

Nishimura, T, Iguchi, M, Hendrasto, M, Aoyama, H

Abstracts of Cities on Volcanoes 8　2014/09
Waveform analysis of explosion earthquake at Lokon-Empung volcano and comparative study of dilatational phase of Vulcanian eruption

Yamada, T, Aoyama, H, Nishimura, T, Yakiwara, H, Nakamichi, H, Oikawa, J, Iguchi, M, Hendrasto, M, Suparman, Y

Abstracts of Cities on Volcanoes 8　2014/09
A2-01 Magma retreat model for volcanic ground deformation associated with a vulcanian eruption

Minowa Takashi, Nishimura Takeshi

Programme and abstracts the Volcanological Society of Japan　2013　20-20　2013/09/29
Publisher: Volcanological Society of Japan
A3-05 Continuous measurements of sulfur dioxide emission rate at Suwanosejima volcano, Southwest Japan

Morita Masaaki, Mori Toshiya, Iguchi Masato, Nishimura Takeshi

Programme and abstracts the Volcanological Society of Japan　2013　43-43　2013/09/29
Publisher: Volcanological Society of Japan
Synthesis of coda wave envelopes in randomly inhomogeneous elastic media in a half space: Single scattering model including Rayleigh waves (vol 172, pg 130, 2008)

T. Maeda, H. Sato, T. Nishimura

GEOPHYSICAL JOURNAL INTERNATIONAL　193　(2)　1050-1051　2013/05

DOI： 10.1093/gji/ggt035 　

ISSN： 0956-540X
A2-02 Analyses of source mechanism of explosion earthquake observed at Lokon-Empung volcano, Indonesia

Yamada T., Aoyama H., Nishimura T., Yakiwara H., Nakamichi H., Iguchi M., Oikawa J., Hendrasto Muhamad, Suparman Yasa

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2013　(0)　21-21　2013
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2013.0_21 　

ISSN： 2433-5320
Source process of explosive eruptions inferred from a seismic array close to the active crater of Suwanosejima volcano, Japan

Nakamichi, H, Aoyama, H, Nishimura, T, Yakiwara, H, Ohta, Y, Yokoo, A, Iguchi, M

AGU Fall meeting 2012　2012/12
A2-08 Magnitude and interval time of vulcanian eruptions : a case study of Sakurajima, Suwanosejima and Semeru volcanoes

Nishimura Takeshi, Iguchi Masato, Hendrasto Muhamad

Programme and abstracts the Volcanological Society of Japan　2012　28-28　2012/10/14
Publisher: Volcanological Society of Japan
A2-05 Classification of volcanic ash samples of Sakurajima volcano using CCD camera image and cluster analysis

Miwa Takahiro, Shimano Taketo, Nishimura Takeshi

Programme and abstracts the Volcanological Society of Japan　2012　25-25　2012/10/14
Publisher: Volcanological Society of Japan
P07 Analyses of initial contraction phase of explosion earthquakes observed at Suwanosejima Volcano

Hirai Y., Nishimura T., Iguchi M., Tameguri T., Oikawa J., Yakiwara H., Nakamichi H., Aoyama H.

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2012　(0)　105-105　2012
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2012.0_105 　

ISSN： 2433-5320
Volcano inflations prior to small vulcanian eruptions at Suwanose-jima volcano, Japan

Nishimura, T, Iguchi, M, Oikawa, J, Yakiwara, H, Aoyama, H, Ohta, Y, Nakamichi, H, Tameguri, T

AGU Fall meeting 2011　2011/12
Envelope synthesis of short-period seismograms in 3-D random media for a point shear dislocation source based on the forward scattering approximation: Application to small strike-slip earthquakes in southwestern Japan

SAWAZAKI Kaoru, SATO Haruo, NISHIMURA Takeshi

Journal of Geophysical Research　116　(B8)　B08305　2011

DOI： 10.1029/2010JB008182 　

ISSN： 0148-0227
B3-09 Array Analysis of Explosion Earthquakes and Tremor observed at Suwanosejima Volcano, southwest Japan

Nakamichi H., Aoyama H., Nishimura T., Yakiwara H., Ohta Y., Yokoo A., Iguchi M.

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2011　(0)　106-106　2011
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2011.0_106 　

ISSN： 2433-5320
マルコフ近似に基づくエンベロープをグリーン関数として用いた断層からの高周波エネルギー輻射量推定法

澤崎郁, 佐藤春夫, 西村太志

日本地震学会秋季大会講演予稿集　2009　2009
2008年桜島人工地震探査の目的と実施

井口正人, 為栗健, 山本圭吾, 大島弘光, 前川徳光, 森済, 鈴木敦生, 筒井智樹, 今井幹浩, 對馬和希, 八木直史, 植木貞人, 中山貴史, 山本芳裕, 高木涼太, 猪井志織, 古賀祥子, 西村太志, Titi ANGGONO, 山本希, 及川純, 長田昇, 市原美恵, 辻浩, 青木陽介, 森田裕一, 渡邊篤志, 野上健治, 山脇輝夫, 渡辺俊樹, 中道治久, 奥田隆, 立花健二, Enrique HERNANDEZ, 橋田悠, 平井敬, 吉本昌弘, 山崎賢志, 毛利拓治, 清水洋, 中元真美, 山下裕亮, 三ケ田均, 尾西恭亮, 田中暁, 岡野豊, 川林徹也, 藤谷淳司, 坂口弘訓, 今泉光智哲, 大倉敬宏, 吉川慎, 安部祐希, 安藤隆志, 横尾亮彦, 相澤広記, 髙山鐵朗, 山崎友也, 多田光弘, 市川信夫, 加茂正人, 富阪和秀, 宮町宏樹, 小林励司, 八木原寛, 平野舟一郎, 泊知里, 西山信吾, 吉田沙由美, 畠山謙吾, 西田誠, 加藤幸司, 宮村淳一, 小枝智幸, 増田与志郎, 平松秀行, 河野太亮, 松末伸一, 大薄富士男, 五藤大仁, 宮下誠, 伊藤弘志, 音成陽二郎

京都大学防災研究所年報　(第52号B)　293-307　2009
Pressure Impulses Generated by Bubbles Interacting with Ambient Perturbation

Ichihara, M, Nishimura, T

Encyclopedia of Complexity and System Science　6955-6977　2009
Publisher: Springer
B17 Effect of the 2008 Iwate-Miyagi Earthquake on the Onikobe Geyser

Nishimura Takeshi, Ueki Sadato, Ichihara Mie

Programme and abstracts the Volcanological Society of Japan　2008　(0)　69-69　2008/10/10
Publisher: 特定非営利活動法人日本火山学会
DOI： 10.18940/vsj.2008.0_69 　

ISSN： 2433-5320
Japanese University Joint Dense Seismic Observation on and around Fuji Volcano (September 2002-April 2005)

Watanabe Hidefumi, Nakamichi Haruhisa, Ohminato Takao, Kagiyama Tsuneomi, Oikawa Jun, Aoki Yosuke, Tsuji Hiroshi, Koyama Etsurou, Osada Noboru, Hagiwara Michinori, Takeda Toyotarou, Kobayashi Masakatsu, Oshima Hiromitsu, Aoyama Hiroshi, Maekawa Tokumitsu, Suzuki Atsuo, Tanaka Satoshi, Nishimura Takeshi, Nita Kouichi, Yamazaki Jun, Okuda Takashi, Yamada Mamoru, Okura Takahiro, Sudo Yasuaki, Yoshikawa Shin, Iguchi Masato, Shimizu Hiroshi, Uehira Kenji, Matsushima Ken, Yakiwara Hiroshi, Hirano Shuichiro

Bulletin of the Earthquake Research Institute, University of Tokyo　82　(3)　195-207　2008/02/25
Publisher: The University of Tokyo
ISSN： 0040-8972
伊豆の衝突と神奈川県西部のテクトニクス稠密地震観測による南部フォッサマグナの地震波速度構造

中道治久, 渡辺秀文, 大湊隆雄, 鍵山恒臣, 及川純, 竹田豊太郎, 小山悦郎, 小林知勝, 長田昇, 辻浩, 大島弘光, 青山裕, 前川徳光, 鈴木敦生, 田中聡, 西村太志, 仁田交市, 山崎純, 萩原道徳, 山岡耕春, 山田守, 大倉敬宏, 須藤靖明, 井口正人, 清水洋, 植平賢司, 松島健, 八木原寛

月刊地球　71-76　2007/02/01

ISSN： 0387-3498
コーダ波解析から推定された強震に伴う地盤浅部速度構造の時間変化

澤崎郁, 佐藤春夫, 中原恒, 西村太志

日本地震学会秋季大会講演予稿集　2007　2007
KiK-net日野観測点における鳥取県西部地震後の地盤増幅特性の異方性とその経時変化の検出

澤崎郁, 佐藤春夫, 中原恒, 西村太志

日本地震学会秋季大会講演予稿集　2006　2006
Rayleigh-wave group velocity in Japan revealed from the cross-correlation analysis of microseisms excited by typhoons

Takagi, N, H. Sato, T. Nishimura, K. Obara

Proceedings of the 8th SEGJ Symposium　2006
レシーバ関数から推定される中部地域の地殻・最上部マントル構造

吉本和生, 藤澤宏篤, 岡田知己, 海野徳仁, 長谷川昭, 小原一成, 汐見勝彦, 塚原弘昭, 岡本茂, 川中卓, 佐藤比呂志, 佐藤春夫, 西村太志, 大竹政和

月刊地球, 号外　50　139-144　2005/04
震源域近傍の強震計アレイにより記録された2005年8月16日宮城県沖の地震(M7.2)

中原恒, 沢崎郁, 西村太志, 佐藤春夫, 藤原広行

日本地震学会秋季大会講演予稿集　2005　2005
B34 Mechanism of the Onikobe geyser

Nishimura T, Sato M, Ueki S, Shimomura Y, Ichihara M

Programme and abstracts the Volcanological Society of Japan　2004　(0)　98-98　2004/10/19
Publisher: 特定非営利活動法人日本火山学会
DOI： 10.18940/vsj.2004.0_98 　

ISSN： 2433-5320
日本の火山性地震・微動のデータベース(共著)

大島弘光, 青山裕, 筒井智樹, 西村太志, 田中聡, 藤田英輔, 熊谷博之, 中道治久, 及川純, 大湊隆雄, 小林知勝, 武尾実, 鬼沢真也, 高木憲朗, 中野優, 井口正人, 為栗健, 須藤靖明, 森健彦, 馬越孝道, 清水洋, 八木原寛

日本の火山性地震・微動のデータベース　649　2004
Broadband source process of the 1998 Iwate prefecture, Japan, earthquake as revealed from inversion analyses of seismic waveforms and envelopes

Hisashi Nakahara, Takeshi Nishimura, Haruo Sato, Masakazu Ohtake, Shigeo Kinoshita, Hiroyuki Hamaguchi

Bulletin of the Seismological Society of America　92　(5)　1708-1720　2002/06

DOI： 10.1785/0120010161 　

ISSN： 0037-1106
火山熱流体シミュレーションと環境影響予測手法の開発 VTFS (I) (1) プロジェクトの概要

藤田英輔, 日高政隆, 海野進, 寅丸敦志, 後藤章夫, 西村太志, 市原美恵, 山本朝男, 諏沢寛源

日本火山学会講演予稿集　2002　2002

ISSN： 2433-5320
Broad-Band Source Process Dedeuced by Inversion of Low-Frequency Waveforms and High-Frequency Seismogram Envelopes: The M6.1 Earthquake of September 3, 1988 in Iwate, Japan (Abstract)

Nakahara Hisashi, Nishimura Takeshi, Sato Haruo, Ohtake Masakazu, Shigeo Kinoshita, Hamaguchi Hiroyuki

The science reports of the Tohoku University. Fifth series, Tohoku geophysical journal　36　(2)　271-271　2001/09
Publisher: Faculty of Science, Tohoku University
ISSN： 0040-8794
Throbs of the Earth-A New Image of Earthquakes and Volcanoes-

NISHIMURA Takeshi

Bulletin of the Volcanological Society of Japan　46　(3)　133-133　2001/06/27
Publisher: Volcanological Society of Japan
ISSN： 0453-4360
Seismic activity associated with the 2000 eruption of Mt. Usu

Oshima H, Mori H, Maekawa T, Yoshida K, Tamura S, Ichiyanagi M, Okada Hm, Hamaguchi H, Nishimura T, Aoyama H, Tsuji H, Uehira K, Miyamachi H, Yakihara H, Sudo Y, Takayama T

Programme and abstracts the Volcanological Society of Japan　2000　(2)　33-33　2000/09/30
Publisher: Volcanological Society of Japan
DOI： 10.18940/vsj.2000.2.0_33 　
Characteristics of Volcanic Earthquakes at Kuchierabujima Volcano-Geophysical and Geochemical Joint Observation 2000-

(44)　317-326　2000
Publisher: 京都大学防災研究所
ISSN： 0386-412X
Source process of very long period Seismic events associated with the 1998 activity of Iwate Volcano, northeasterm Japan,

Nishimura, T, H. Nakamichi, S. Tanaka, H. Sato

J. Geophys. Res.　105　(B8)　19135-19147　2000

DOI： 10.1029/2000JB900155 　

ISSN： 0148-0227
Seismic Activity of Bandai Volcano from April to July, 2000

Nishimura T., Ueki S., Tanaka S., Tachibana K., Nakamichi H., Sato M., Yamawaki T., Hamaguchi H.

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　2000　(0)　93-93　2000
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.2000.2.0_93 　

ISSN： 2433-5320
Source process of volcanic long-period earthquakes and tremor as inferred from one-dimensional compressible flow model

NISHIMURA Takeshi

1999　(2)　A49　1999/11/09
Spatial Distribution of High-Frequency Seismic Wave Energy radiation on the Fault Plane of the Northern Iwate Prefecture earthquake of September 3, 1998.

NAKAHARA Hisashi, NISHIMURA Takeshi, SATO Haruo, OHTAKE Masakazu, KINOSHITA Shigeo, HAMAGUCHI Hiroyuki

1999　(2)　A58　1999/11/09
1998年9月3日岩手県内陸北部の地震（Ｍ6.1）の断層近傍で記録された強震動

中原恒, 西村太志, 佐藤春夫, 大竹政和, 木下繁夫, 三浦哲, 植木貞人, 浜口博之

月刊地球　21　322-326　1999/04
Near-source strong-motion records of the northern part of Iwate Prefecture earthquake (M6.1) of September 3, 1998

NAKAHARA Hisashi, NISHIMURA Takeshi, SATO Haruo, OHTAKE Masakazu, KINOSHITA Shigeo, MIURA Satoshi, UEKI Sadato, HAMAGUCHI Hiroyuki

1998　(2)　1998/10/09
Moment tensor inversion of long-period seismic events observed at Mount Iwate

NISHIMURA Takeshi, NAKAMICHI Haruhisa, TANAKA Satoru, SATO Minemori, UEKI Sadato, HAMAGUCHI Hiroyuki, OHTAKE Masakazu, SATO Haruo

日本地震学会講演予稿集 = Programme and abstracts, the Seismological Society of Japan　1998　(2)　1998/10/09
1995 Explosion Experiment in Unzen Volcano

松島健, 清水洋, 西村裕一, 植木貞人, 西村太志, 青木重樹, 早川俊彦, 鍵山恒臣, 三ヶ田均, 及川純, 北村健彦, 宗包浩志, 渡辺了, 熊谷博之, 筒井智樹, 西潔, 井口正人, 宮町宏樹, 高木朗充, 岡田弘, 前川徳光, 青山裕, 千野真, 奥喜明, 為栗健, 森田裕一, 橋本恵一, 中道治久, 佐藤峰司, 平林順一

東京大學地震研究所彙報 = Bulletin of the Earthquake Research Institute, University of Tokyo　72　(2)　167-183　1998/03/20
Publisher: 東京大学地震研究所
ISSN： 0040-8972

More details Close

In 1995, the second joint seismic experiment for investigations on the structures of volcanoes was conducted on Unzen Volcano, Western Kyushu, by a group of scientists from national universities and under the National Research Project for the Prediction of Volcanic Eruptions. Mt. Fugen, the main peak of Unzen volcano, abruptly started eruption in November, 1990, and the eruption continued till early 1995. A new lava dome was formed on the east side of Mt. Fugen and pyroclastic flows were generated from the lava dome. The estimated volume of magma erupted in this activity was 2xl08m3. To reveal the structure and the magma supply system under the volcano is one of the major aim of this experiment. A set of extensive explosion seismic experiments was conducted on November 30, 1995. Observations were made along a 26-km line and a 12-km line lying in the WNW-ESE and NNE-SSW directions respectively, and 5 small aperture arrays. The two lines cross on the western flank of the volcano. Six shots by chemical explosives with a charge size of 200-250 kg and 295 temporary seismic observations were arranged. All 6 shots were successfully fired, and clear onset and significant phases of seismic waves were recorded on compact data-loggers with precise GPS clock at most observation sites. The travel time curves of the first arrivals suggest that higher velocity region exists beneath the western flank of the volcano. In the observed records, we also found a number of remarkable later phases which are interpreted as reflected and scattered waves from the structure under the volcano. An outline of this experiments is given briefly in this paper, and detailed results of the experiments will be published later in separate papers.
Seismogram envelope inversion for the spatial distribution of high-frequency energy radiation from the earthquake fault : Application to the 1994 far east off Sanriku earthquake, Japan

Nakahara, H, T. Nishimura, H. Sato, M. Ohtake

J. Geophys. Res.　103　(B1)　855-867　1998

DOI： 10.1029/97JB02676 　

ISSN： 0148-0227
Long-period seismic events observed at Mount Iwate

Nishimura Takeshi, Nakamichi Haruhisa, Tanaka Satoru, Sato Minemori, Ueki Sadato, Hamaguchi Hiroyuki, Ohtake Masakazu, Sato Haruo

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　1998　(0)　6-6　1998
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.1998.2.0_6 　

ISSN： 2433-5320
Volcanic Tremor Array Observation Using Three Components Seismometers at Iwate Volcano

Nakamichi H., Hamaguchi H., Yamamoto H., Tanaka S., Nishimura T., Iwasawa T., Hirono T., Yamawaki T., Ueda H., Saito T.

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　1998　(0)　83-83　1998
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.1998.2.0_83 　

ISSN： 2433-5320
Estimation of Shallow Underground Velocity Structure from Microtremor Array Observation at lwate Volcano

Yamamoto H., Hamaguchi H., Nakamichi H., Iwasawa T., Hirono T., Tanaka S., Nishimura T., Yamawaki T., Ueda H., Saito T.

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　1998　(0)　84-84　1998
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.1998.2.0_84 　

ISSN： 2433-5320
The March, 1996 Mt. Komagatake Eruption (part 1)

Okada H, Mori H, Nishimura Y, Oshima H, Maekawa T, Suzuki A, Hoshino S, Ordonez M, Jousset P

Programme and abstracts the Volcanological Society of Japan　1996　(2)　77-77　1996/11/05
Publisher: Volcanological Society of Japan
DOI： 10.18940/vsj.1996.2.0_77 　
KiRiSiMA-1994 Explosion EXPERiMENT : Analyses with the method of difference

Tsutsui T., Watanabe T., Nishimura Y., Nishimura T., Yamaoka K., Kumagai H., Takagi A., Kagiyama T., Mikada H., Oikawa J., Yamamoto K., Matsushima T., Miyamachi H., Morita Y., Iguchi M.

PROGRAMME AND ABSTRACTS THE VOLCANOLOGICAL SOCIETY OF JAPAN　1995　(0)　97-97　1995
Publisher: The Volcanological Society of Japan
DOI： 10.18940/vsj.1995.2.0_97 　

ISSN： 2433-5320
Development of Small Digital Data Logger with Global Positioning System

NISHIMURA Takeshi, MORITA Yu'ichi, HAMAGUCHI Hiroyuki

Zisin : Journal of the Seismological Society of Japan　47　(1)　79-83　1994/06/14
Publisher: 日本地震学会
ISSN： 0037-1114
Joint Seismometrical Observations by the National University Team during the 1988-1989 Eruptive Activity of Mt.Tokachi, Hokkaido : Special Section: The 1988-1989 Eruption of Mt・ Tokachi, Central Hokkaido

NISHIMURA Yu'ichi, MIYAMACHI Hiroki, UEKI Sadato, NISHIMURA Takeshi, SHIMIZU Hiroshi, OHMI Shiro, OKADA Hiromu

Bulletin of the Volcanological Society of Japan. Second series　35　(2)　163-173　1990/07/02
Publisher: Volcanological Society of Japan
ISSN： 0453-4360

More details Close

During the 1988-1989 eruptive activity of Mt.Tokachi, repeated field observations and strengthened efforts for seismometrical observations were made by the National University Team. Nine eruptions during the later eruptive period were observed by three temporary seismic projccts; (1) a new seismic station (HNG) installed at the possible nearest site to the 62-II crater, (2) a small array and (3) nine temporary seismic stations using direct recording system at the volcano and surroundings. These observations revealed that both low-frequency earthquakes (LF) and volcanic tremors (TR) were characterized by Rayleigh type surface waves. The incident azimuths and the apparent velocities at the array are common for both LF and TR. They are inferred to be originated from the limited small region at the shallow depth beneath the 62-II crater. On the other hand, the wave characteristics and the sources of explosion earthquakes (EX) are different from those of LF and TR. EX are inferred to be located beneath the crater, but their depths are somewhat variable.
21B. Seismicity of the Bandai volcano.(Abstracts of Papers Presented at the Fall Meeting of the Society)

Hamaguchi H., Ueki S., Nishimura T., Umezu I., Hashimoto K.

Bulletin of the Volcanological Society of Japan. Second series　34　(4)　331-331　1989/12
Publisher: Volcanological Society of Japan
ISSN： 0453-4360
15A. Volcanic tremor associated with the Teishi-Kaikyu eruption, off the Izu peninsula.(Abstracts of Papers Presented at the Fall Meeting of the Society)

Nishimura T., Ueki S., Morita Y., Hamaguchi H.

Bulletin of the Volcanological Society of Japan. Second series　34　(4)　313-314　1989/12
Publisher: Volcanological Society of Japan
ISSN： 0453-4360
14A. Precisely determined hypocenter distribution of the earthquakes following the eruption of Teishi-Kaikyu Volcano, off the Izu peninsula.(Abstracts of Papers Presented at the Fall Meeting of the Society)

Ueki S., Morita Y., Horiuchi S., Nishimura T., Tanaka S., Hashimoto K., Hamaguchi H.

Bulletin of the Volcanological Society of Japan. Second series　34　(4)　313-313　1989/12
Publisher: Volcanological Society of Japan
ISSN： 0453-4360
35. Seismic Observation Associated with the 1989 Eruptive Activity of Mt. Tokachi by the Use of Small Array.(Abstracts of Papers Presented at the Spring Meeting of the Society)

Nishimura T., Ueki S., Miyamachi H., Nishimura Y.

Bulletin of the Volcanological Society of Japan. Second series　34　(2)　140-140　1989/07/25
Publisher: Volcanological Society of Japan
ISSN： 0453-4360
56B. Seismic observation in the summit crater of Volcano Nyamuragira in 1988.(Abstracts of Papers Presented at the Spring Meeting of the Society)

Nishimura T., Kasahara M., Tanaka K., Hayashi S., Seto M., Hamaguchi H., Mukeng K., Kavotha S. K., Lukaya N., Zana N.

Bulletin of the Volcanological Society of Japan. Second series　34　(2)　155-156　1989/07/25
Publisher: Volcanological Society of Japan
ISSN： 0453-4360
4. The 1977 eruptive process of Volcano Nyiragongo.(Abstracts of Papers Presented at the Fall Meeting of the Society)

Nishimura T., Hamaguchi H., Zana N.

Bulletin of the Volcanological Society of Japan. Second series　33　(4)　322-323　1988/12/28
Publisher: Volcanological Society of Japan
ISSN： 0453-4360

Show all ︎Show first 5

Books and Other Publications 7

現代地球科学入門シリーズ7 「火山学」

吉田武義, 西村太志, 中村美千彦

共立出版　2017/05
現代地球科学入門シリーズ６「地震学」

長谷川昭, 佐藤春夫, 西村太志

共立出版　2015/08/25
Volcanic earthquakes and tremor in Japan

Nishimura, T, Iguchi, M

Kyoto Univ. Press　2011/02
「火山爆発に迫る－噴火メカニズムの解明と火山災害の軽減」（井田喜明・谷口宏充編）

西村太志

東大出版会　2009/02/20
Encyclopedia of Complexity and Systems Science

Ichihara, M, Nishimura, T

Springer　2009
火山の事典

西村太志, 浜口博之

朝倉書店　2008/06/30
日本の火山性地震と微動

西村太志, 井口正人

京都大学学術出版会　2006/02/10

Show all Show first 5

Presentations 139

我が国の火山調査研究・火山防災体制 Invited

西村太志

地域安全学会オンライン火山防災対策勉強会（第４回）「これからの火山防災を考える」　2024/12/14
新聞データベースにもとづく大地震・火山噴火後の報道量の時間変化の特徴

西村太志, 齋藤さやか

日本災害情報学会第29回学会大会　2024/11
複素主成分分析を用いたDASで記録された吾妻山火山性地震の震源決定

西村太志, 森作史哉, 中原恒, 山本希, 三浦哲, 江本賢太郎

日本火山学会2024年度秋季大会　2024/10
桜島 DAS により観測された土石流に伴う地盤振動波形データの振幅および位相解析

田口貴美子, 西村太志, 中原恒, 廣瀬郁, 中道治久, 江本賢太郎, 濱中悟

日本火山学会2024年度秋季大会　2024/10
桜島における DAS を用いた爆発地震の発震機構の推定

長谷川誉久, 西村太志, 中原恒, 廣瀬郁, 田口貴美子, 中道治久, 江本賢太郎, 濱中悟

日本火山学会2024年度秋季大会　2024/10
データベースからみえる地震と火山の相互作用 Invited

西村太志

第243回地震予知連絡会　2024/05/22
中原恒・西村太志・田口貴美子・廣瀬郁・矢武克啓・中道治久・江本賢太郎・濱中悟

光ファイバーの屈曲点付近のDASデータを用いた, 次元歪テンソルの推定

日本地球惑星科学連合2024年大会　2024/05
DASデータの地震波干渉法解析による桜島における地震波速度変化の推定

廣瀬郁・西村太志・中原恒・田口貴美子・中道治久・江本賢太郎・濱中悟

日本地球惑星科学連合2024年大会　2024/05
Joint analysis of seismic velocity change, deformationand meteorological data for volcano monitoring

Joint analysis of, seismic velocity change, deformationand, meteorological data for, volcano monitoring

2024/05
Source location of volcanic earthquakes using ASL method invelocity structure having a constant vertical gradient

Novia Antika Anggraeni, Takeshi Nishimura, Hisashi Nakahara

2024/05
DAS記録に含まれる交通振動を用いた国道47号線沿道の浅部地震波速度構造の推定

矢武克啓・中原恒・江本賢太郎・西村太志

日本地球惑星科学連合2024年大会　2024/05
桜島における爆発地震の発震機構のフォワードモデリング

長谷川誉久, 西村太志

日本地球惑星科学連合2024年大会　2024/05
Joint analysis of seismic velocity change, deformation and meteorological data for volcano monitoring

Quentin Dumon, Takeshi Nishimura, Takashi Hirose, Tomoya Takano

EGU General Assembly　2024/04
DAS システムにより観測された 2022 年 11 月 29日桜島野尻川沿い土石流に伴う地盤振動波形の解析

田口貴美子, 西村太志, 中原恒廣瀬, 郁, 中道治久, 江本賢太郎, 濱中悟

日本火山学会2023年度秋季大会　2023/10/20
霧島硫黄山のガス噴出現象の地震波解析

畑誠斗, 西村太志, 松島健, 村松, 弾, 長妻努, 村田健史, 小園誠史, 田辺暖柊

日本火山学会2023年度秋季大会　2023/10/20

More details Close

本学修士学生
DAS 観測による桜島の爆発地震の解析

西村太志, 田口貴美子, 中原恒, 畑誠斗, 中道治久, 高橋龍平, 江本賢太郎, 濱中悟, 小園誠史, 長妻努, 村田健史, 菊田和孝

日本火山学会2023年度秋季大会　2023/10/18

More details Close

本人
桜島火山における爆発地震波形の数値計算

長谷川誉久, 西村太志

日本火山学会2023年度秋季大会　2023/10/18

More details Close

本学修士学生
映像IoTシステムによる火山のリアルタイム噴煙検出

菊田和孝, 村田健史, 西村太志

日本地球惑星科学連合2023年大会　2023/05/25
霧島硫黄山南火口群における表面活動の長期的変化

村松弾, 松島健, 長妻努, 村田健史, 西村太志, 畑誠斗, 田辺暖柊

日本地球惑星科学連合2023年大会　2023/05/25
火山研究人材育成コンソーシアム構築事業における大学・自治体・民間企業の連携と今後の展望 ―火山防災特別セミナーを軸に―

齋藤さやか, 西出則武, 地引泰人, 西村太志

日本地球惑星科学連合2023年大会　2023/05/23
火山人材育成コンソーシアム構築事業の概要と現状

西村太志

日本地球惑星科学連合2023年大会　2023/05/23

More details Close

本人
2022年光ファイバーとDAS観測による桜島の地震動記録

西村太志, 江本賢太郎, 中道治久, 濱中悟, 中原恒, 田口貴美子

日本地球惑星科学連合2023年大会　2023/05/21

More details Close

本人
橋梁により連続的に生成される表面波のDAS記録を利用した浅部地盤構造モニタリング

矢武克啓, 中原恒, 江本賢太郎, 西村太志

日本地球惑星科学連合2023年大会　2023/05/21

More details Close

本学博士学生
2022年9月19日に観測された霧島硫黄山南火口群における特異的な表面活動

長妻努, 村田健史, 菊田和孝, 村上雄樹, 松島健, 村松弾, 田辺暖柊, 西村太志

日本地球惑星科学連合2023年大会　2023/05/20
光ファイバーケーブルとDASを利用した地盤構造探査

西村太志

2023年度東北大学タフ・サイバーフィジカルAI研究センターシンポジウム　2023/04/20

More details Close

本人
火山研究人材育成コンソーシアム構築事業の概要 Invited

西村太志

第28回日本災害医学会総会　2023/03
国道4号線におけるDAS，ビデオカメラ，広帯域地震計による通過車両の同時観測

矢武克啓, 中原恒, 江本賢太郎, 西村太志

日本地震学会2022年度秋季大会　2022/10
桜島爆発的噴火の発生場所

西村太志

日本火山学会2022年度秋季大会　2022/10
DASデータへの複素数主成分分析の適用による相対震源決定─吾妻山の火山性地震の解析─

森作史哉, 西村太志, 中原恒, 江本賢太郎

日本火山学会2022年度秋季大会　2022/10
Source Location Determination of Volcanic Earthquakes at Sakurajima Volcano using CCF based SSA Method

Novia Antika Anggraeni, Takeshi Nishimura, Hisashi Nakahara

2022/10
光ファイバーケーブルとDASによる火山観測 Invited

西村太志

第236回地震予知連絡会　2022/08/29
東北地方における3成分回転地震計を用いた地震動の回転成分の観測

中原恒, 山本希, 熊木健人, 池谷拓馬, 高木涼太, 江本賢太郎, 西村太志

日本地球惑星科学連合2022年大会　2022/05
Relative Hypocenter Determination of Volcanic earthquakes at Mt. Azuma using DAS System

2022/05
間欠泉噴出過程の短周期振動－熱赤外映像および空振観測からの考察－

手嶌法子, 西村太志

日本火山学会2021年秋季大会　2021/10
桜島の爆発的な噴火に伴い発生する地震の震源決定

三浦健司, 西村太志

日本火山学会2021年度秋季大会　2021/10
大地震による火山噴火誘発のメカニズム

西村太志

日本地震学会2021年度秋季大会　2021/10
国道４号線沿いのDAS観測により捉えられた移動車両が励起する表面波を直接利用した浅部S波速度構造の推定

矢武克啓, 中原恒, 江本賢太郎, 西村太志

日本地震学会2021年度秋季大会　2021/10
Heterogeneity of active volcanoes in Japan as inferred from the peak ratio analysis of scattered teleseismic P waves

Gugi Ganefianto, Hisashi Nakahara, Takeshi Nishimura

IAGA-IASPEI Joint Scientific Assembly 2021　2021/08
Estimation of the shallow small-scale heterogeneity by using the dense DAS data

Kentaro Emoto, Hisashi Nakahara, Takeshi Nishimura, Mare Yamamoto, Kodai Sagae, Gugi Ganefianto, Yabu Katsuhiro

IAGA-IASPEI Joint Scientific Assembly 2021　2021/08
Enhancing the Extraction of Surface-wave Dispersion Curves from the Traffic Signal in DAS Data

Katsuhiro Yabu, Hisashi Nakahara, Kentaro Emoto, Takeshi NishimuraJap

IAGA-IASPEI Joint Scientific Assembly 2021　2021/08
分布型音響計測（DAS）による国道4号線沿いのサイト増幅特性の稠密な空間分布の推定

江本賢太郎, 中原恒, 西村太志, 山本希

日本地球惑星科学連合2021年大会　2021/05
ハフ変換を用いた深部低周波微動の微細な時空間構造の抽出

寒河江皓大, 中原恒, 西村太志, 今西和俊

日本地球惑星科学連合2021年大会　2021/05
Scattering properties in Japanese volcanoes as inferred from the peak ratio analysis of teleseismic P waves using the JMA seismometer network data

Gugi Aucklandi Ganefianto, Hisashi Nakahara, Takeshi Nishimura

日本地球惑星科学連合2021年大会　2021/05
GNSSデータを用いた八重山諸島における平均変位速度ベクトルの推定

池内葵, 加納将行, 中原恒, 西村太志, 駒野和基, 西村卓也, 宮崎真一

日本地球惑星科学連合2021年大会　2021/05
吾妻山の浅部地盤増幅特性の推定―光ファイバーとDASの記録の解析―

西村太志, 江本賢太郎, 中原恒, 三浦哲, 山本希, 杉村俊輔, 石川歩, 木村恒久

日本地震学会2020年秋季大会　2020/10
市街地における光ファイバーケーブルを用いたDAS観測による高密度データの解析

江本賢太郎, 中原恒, 西村太志, 山本希, 寒河江皓, 大, Ganefianto Gugi, 矢武克啓

日本地震学会2020年秋季大会　2020/10
DASによる歪記録に対するSPAC的表現の解析的導出

中原恒, 江本賢太郎, 西村太志

日本地震学会2020年秋季大会　2020/10
Frequency Dependency of the Peak Energy Ratios for Teleseismic P Waves at the Hi-net Stations

Gugi Aucklandi Ganefianto, Hisashi Nakahara, Takeshi Nishimura

日本地震学会2020年秋季大会　2020/10
ストロンボリ火山 2019 年 7 月爆発的噴火の前駆的傾斜変動

石川歩, 西村太志

2020/10
GPS 搬送波位相遅延量を利用した噴煙検知－2013 年 8 月 18 日桜島噴火の解析－

朝倉由香子, 西村太志, 太田雄策, 加納将行, 井口正人

日本火山学会2020年秋季大会　2020/10
大地震による火山噴火の誘発の要因

西村太志

日本火山学会2020年秋季大会　2020/10
光ファイバーとDASの記録を用いた吾妻山の火山性地震の震源決定

西村太志, 江本賢太郎, 中原恒, 三浦哲, 山本希, 杉村俊輔, 植田尚大, 石川歩, 木村恒久

JpGU - AGU Joint Meeting 2020: Virtual　2020/07
2次元1次等方散乱モデルに基づくDASによるエンベロープのモデリング

中原恒, 江本賢太郎, 西村太志

JpGU - AGU Joint Meeting 2020　2020/07
Spatio-temporal clustering of successive earthquakes in Japan: analyses of F-net catalogue

Thystere Matondo Bantidi, Takeshi Nishimura

JpGU - AGU Joint Meeting 2020　2020/07
Estimation of the spatial distribution of Qs values beneath the Kii Peninsula, Japan by the twofold spectral ratio method

寒河江皓大, 中原恒, 西村太志, 今西和俊

JpGU - AGU Joint Meeting 2020　2020/07
Fluid ascent dynamics of the Onikobe geyser, NE Japan: Insight from the thermal infrared imagery

手嶌法子, 西村太志, 青山裕, 柘植鮎太

JpGU - AGU Joint Meeting 2020
桜島の噴火に伴うGPS衛星電波の搬送波位相遅延量の変化－2013年から2019年のデータ解析－

朝倉由香子, 西村太志, 太田雄策, 加納将行

JpGU - AGU Joint Meeting 2020: Virtual
吾妻山における光ファイバーとDASによる地震観測

西村太志, 江本賢太郎, 中原恒, 三浦哲, 山本希, 杉村俊輔, 植田尚大, 石川歩, 木村恒久

日本地震学会2019年秋季大会　2019/09
光ファイバーとDASを用いた吾妻山における地震観測:稠密観測による不均質構造の推定

江本賢太郎, 西村太志, 中原恒, 三浦哲, 山本希, 杉村俊輔, 植田尚大, 石川歩, 木村恒久

日本地震学会2019年秋季大会　2019/09
Spatio-temporal clustering of successive earthquakes in Japan: analyses of JMA catalogue

Bantidi Matondo Thystere, Nishimura Takeshi

2019/09
Comparison of Source Location Methods: CCF-based SSA and ASL

Theodorus Permana, Takeshi Nishimura, Hisashi Nakahara

2019/09
光ファイバーとDAS を用いた吾妻山における地震観測

西村太志, 江本賢太郎, 中原恒, 三浦哲, 山本希, 杉村俊輔, 植田尚大, 石川歩, 木村恒久

日本火山学会2019年秋季大会　2019/09
長周期地震の震源決定と地震・空振の初動解析に基づくストロンボリ火山の火道内マグマ挙動の推定

杉村俊輔, 西村太志, Maurizio Ripepe, Giorgio Lacanna, Denis Legrand, Sébastien Valade

日本火山学会2019年秋季大会　2019/09
ストロンボリ火山の2014年8月山腹噴火に伴う山体変形

石川歩, 西村太志, 青山裕, 川口亮平, 藤田英輔, 三輪学央, 山田大志, Maurizio Ripepe

日本火山学会2019年秋季大会　2019/09
光ファイバーとDAS を用いた吾妻山の不均質構造の推定

江本賢太郎, 西村太志, 中原恒, 三浦哲, 山本希, 杉村俊輔, 植田尚大, 石川歩, 木村恒久

日本火山学会2019年秋季大会　2019/09
光学式ディスドロメータによる降灰測定：噴煙観測におけるレーダーパラメータへの制

小園誠史, 井口正人, 三輪学央, 真木雅之, 前坂剛, 味喜大介, 西村太志

日本地球惑星科学連合2019年大会　2019/05
地震計アレイデータの逆投影による紀伊半島下の深部低周波微動の震源決定

寒河江皓大, 中原恒, 西村太志, 今西和俊

日本地球惑星科学連合2019年大会　2019/05
輻射伝達理論に基づくSコーダ波エンベロープのインバージョン解析－伊豆大島火山の不均質構造の推定－

植田尚大, 西村太志

日本地球惑星科学連合2019年大会　2019/05
活火山の地震波速度変化モニタリング－2012年から2018年の気象庁観測点データへの地震波干渉法の適用―

西村太志, 高野智也, 廣瀬郁, 中原恒

日本地球惑星科学連合2019年大会　2019/05
Mohammad Hasib・Takeshi Nishimura・Hisashi Nakahara

Mohammad Hasib, Takeshi Nishimura, Hisashi Nakahara

2019/05
ストロンボリ火山の山頂小爆発に伴う傾斜変動の圧力源推定

石川歩, 西村太志, 青山裕, 川口亮平, 藤田英輔, 三輪学央, 山田大志, Ripepe Maurizio, Genco Riccardo

日本地球惑星科学連合2019年大会　2019/05
火口極近傍観測に基づくストロンボリ火山の超長周期地震のモーメントテンソルインバージョン

杉村俊輔, Maurizio Ripepe, Giorgio Lacanna, Denis Legrand, Sébastien Valade, 西村太志

日本地球惑星科学連合2019年大会　2019/05
Spatio-temporal clustering of successive earthquakes: data analyses of global data

Thystere Matondo Bantidi, Takeshi Nishimura

2019/05
Source location of volcanic earthquakes and tremors at Sakurajima volcano based on seismic correlation

Theodorus Permana, Takeshi Nishimura, Hisashi Nakahara

2019/05
Estimation of spatio-temporal changes of seismic scattering property associated with the 2008 Iwate-Miyagi Nairiku earthquake from sparse modeling of seismic ambient noise CCFs

2019/05
Estimation of scattering and intrinsic absorption parameters using envelopes of ambient seismic noise cross-correlation function

2019/05

More details Close

本学学生
Moment tensor inversion of very-long-period seismicity observed in a very-near-field condition at Stromboli volcano

Shunsuke Sugimura, Maurizio Ripepe, Giorgio Lacanna, Denis Legrand, Sebastien Valade, Takeshi Nishimura

EGU General Assembly　2019/04
MUSIC 法を用いた紀伊半島周辺の深部低周波微動のアレイ解析

2018/10

More details Close

本学学生
Analysis of seismo-acoustic signals associated to volcanic eruptions at Stromboli volcano International-presentation

Shunsuke Sugimura, Maurizio Ripepe, Giorgio Lacanna, Denis Legrand, Sebastien Valade, Takeshi Nishimura

Cities on Volcanoes 10　2018/09

More details Close

本学学生
Volcanic tremor source location based on seismic cross-correlations: application to synthetic tremor using volcano-tectonic earthquakes International-presentation

Theodorus Permana, Takeshi Nishimura, Hisashi Nakahara, Eisuke Fujita, Hideki Ueda

Cities on Volcanoes 10　2018/09

More details Close

本学学生
Spectral ratio analyses of explosion earthquakes at Sakurajima volcano, Japan International-presentation

Hasib Mohammad, Takeshi Nishimura, Hisashi Nakahara

Cities on Volcanoes 10　2018/09

More details Close

本学学生
Ground deformations associated with recent phreatic eruptions in Japan International-presentation

Takeshi Nishimura

Cities on Volcanoes 10　2018/09
東北地方の火山の噴火活動の特徴

西村太志

日本火山学会2018年秋季大会　2018/09
Source Location Determination of Volcanic Tremor on August 23, 2017, at Sakurajima Volcano

2018/09

More details Close

本学学生
Vulcanian eruption at Sakurajima volcano

2018/09

More details Close

本学学生
ストロンボリ火山の山頂小爆発活動に伴う傾斜変動(2)

2018/05

More details Close

本学学生
ストロンボリ火山の山頂小爆発活動に伴う傾斜変動

2018/05

More details Close

本学学生
Triggering and Coulomb stress interaction of Successive large earthquakes

Thystere M. Bantidi, Takeshi Nishimura

2018/05

More details Close

本学学生
Topography Effect on Spectral Ratio Analysis of Explosion Earthquakes at Sakurajima

Mohammad Hasib, Takeshi Nishimura, Hisashi Nakahara

2018/05

More details Close

本学学生
Source location determination based on seismic cross-correlations: application to simulated tremor using volcano-tectonic earthquakes

Theodorus Permana, Takeshi Nishimura, Hisashi Nakahara, Eisuke Fujita, Hideki Ueda

2018/05

More details Close

本学学生
火山噴火による中規模地震の誘発

西村太志

日本地球惑星科学連合2018年大会　2018/05
Interaction between volcanic eruptions and earthquakes International-presentation

Takeshi Nishimura

2018/04
Seismic velocity changes in response to different direction of tidal strain International-presentation

Tomoya Takano, Takeshi Nishimura, Hisashi Nakahara

EGU Geeral Assembly　2018/04

More details Close

本学学生
Estimation of strain sensitivity of seismic velocity changes using the Earth tide: Analyses of seismic small array data at Izu-Oshima volcano, Japan

Tomoya Takano, Takeshi Nishimura, Hisashi Nakahara, Hideki Ueda, Eisuke Fujita

AGU Fall Meeting 2018　2017/12

More details Close

本学学生
Seismic Activity Around Active Volcanoes for Five Years After the 2011 Tohoku-Oki Earthquake (Mw9.0)

AGU Fall Meeting 2018　2017/12

More details Close

本人
雑微動の相互相関関数を用いた2015年8月15日桜島のダイク貫入に伴う地震波散乱特性の時空間変化イメージング

日本地震学会2017年秋季大会　2017/10/09

More details Close

本学学生
地球潮汐による地震波速度変化の歪み感度の推定ー伊豆大島における地震計小アレイデータの相関解析ー

高野智也, 西村太志, 中原恒, 上田英樹, 藤田英輔

日本地震学会2017年秋季大会　2017/10/09

More details Close

本学学生
室内実験及びStromboli空振観測のMUSIC法による小規模アレイ解析

山河和也, 石井杏佳, 市原美恵, 青山裕, 西村太志

日本火山学会2017年秋季大会　2017/09/22

More details Close

その他
ストロンボリ火山の山腹噴火前のキツツキ地震活動 (2)

近藤弦, 青山裕, 西村太志, 川口亮平, 山田大志, 三輪学央, 藤田英輔, Ripepe Maurizio, Genco Riccardo

日本火山学会2017年秋季大会　2017/09/22

More details Close

その他
2015年6月の臨時観測によるストロンボリ火山の噴火地震のメカニズム推定

杉村俊輔, 西村太志, 青山裕, 川口亮平, 藤田英輔, 三輪学央, 山田大志, Ripepe Maurizio, Genco Riccardo

日本火山学会2017年秋季大会　2017/09/22

More details Close

本学学生
地震波干渉法を用いた2015年8月15日桜島のダイク貫入に伴う地震波散乱特性の時空間変化イメージング

廣瀬郁, 中原恒, 西村太志

日本火山学会2017年秋季大会　2017/09/22

More details Close

本学学生
地球潮汐を用いた，伊豆大島浅部構造における地震波速度変化の歪み感度の推定ー小地震計アレイで記録された雑微動の相関解析ー

高野智也, 西村太志, 中原恒, 上田英樹, 藤田英輔

日本火山学会2017年秋季大会　2017/09/22

More details Close

本学学生
地震波速度の潮汐応答特性の推定：13活火山における雑微動の相関解析

高野智也, 西村太志, 中原恒

日本地球惑星科学連合2017年大会　2017/05/20

More details Close

本学学生
Triggering of volcanic eruptions: stress transfer by large earthquakes

西村太志

日本地球惑星科学連合2017年大会　2017/05/20

More details Close

本人
Detection of spatio-temporal changes of seismic scattering properties with seismic interferometry: Dike intrusion event on 15 August 2015 at Sakurajima volcano

廣瀬郁, 中原恒, 西村太志

日本地球惑星科学連合2017年大会　2017/05/20

More details Close

本学学生
Seismic analyses of Vulcanian eruption at Sakurajima volcano: Spectral ratio analyses of explosion and Volcano-tectonic earthquakes

Hasib Mohammad, Takeshi Nishimura

日本地球惑星科学連合2017年大会　2017/05/20

More details Close

本学学生
大地震による火山噴火の誘発

西村太志

日本火山学会2016年秋季大会　2016/10/13

More details Close

本人
伊豆大島における地殻変動と地震波速度変化 −気象庁データの解析−

高野智也, 西村太志, 中原恒

日本火山学会2016年秋季大会　2016/10/13

More details Close

本学学生
地震波干渉法に基づく2015年8月15日桜島のダイク貫入に伴う地震波散乱特性の時空間変化の検出

廣瀬郁, 中原恒, 西村太志

日本火山学会2016年秋季大会　2016/10/13

More details Close

本学学生
2011年東北地方太平洋沖地震後の火山性地震と噴火活動の変化

西村太志

日本地震学会2016年秋季大会　2016/10/05

More details Close

本人
地震波干渉法により検出した2015年8月15日桜島のダイク貫入に伴う地震波散乱特性の時空間変化

廣瀬郁, 中原恒, 西村太志

日本地震学会2016年秋季大会　2016/10/05

More details Close

本学学生
測地データと火道流モデルの比較

日本地球惑星科学連合2016年大会　2016/05/22

More details Close

本人
グローバルデータに基づく大地震連発性の発生確率－熊本の連続地震発生を受けて－

日本地球惑星科学連合2016年大会　2016/05/22

More details Close

本人
ノイズ相関解析に基づく火山における地震波速度変化の特徴―気象庁データの解析―

高野智也, 西村太志, 中原恒

日本地球惑星科学連合2016年大会　2016/05/22

More details Close

本学学生
Spectral Ratio Analysis of Explosion Earthquakes at Sakurajima Volcano

Mohammad Hasib, Takeshi Nishimura

日本地球惑星科学連合2016年大会　2016/05/22

More details Close

本学学生
2015年6月の臨時観測によるストロンボリ火山の噴火地震の相対震源決定

杉村俊輔, 西村太志, 青山裕, 山田大志, 川口亮平, 三輪学央, 藤田英輔, Ripepe Maurizio, Genco Riccardo

日本地球惑星科学連合2016年大会　2016/05/22

More details Close

本学学生
桜島火山の噴火前後に観測される傾斜変動の特徴―気象庁あみだ川観測点データの解析―

中島稜介, 西村太志

日本地球惑星科学連合2016年大会　2016/05/22

More details Close

本学学生
拡散・減衰モデルに基づく北海道東部における地震波減衰特性の推定

金谷希美, 江本賢太郎, 中原恒, 西村太志

日本地球惑星科学連合2016年大会　2016/05/22

More details Close

本学学生
火山性地震の発生時系列と噴火発生－近年の日本の事例から－

西村太志, 高木朗充

日本火山学会2015年秋季大会　2015/09/28

More details Close

本人
Detecting seismic velocity changes at Sakurajima volcano, Japan by seismic interferometry and coda wave interferometry

Hirose,T, H. Nakahara, T. Nishimura

IUGG 2015　2015/06/22

More details Close

その他
傾斜記録から推定される小規模爆発過程－新燃岳，口永良島, 御嶽山－

西村太志

日本地球惑星科学連合2015年大会　2015/05/24

More details Close

本人
コーダ波干渉法と地震波干渉法の併用により検出した桜島の地震波速度構造の時間変化

廣瀬郁, 中原恒, 西村太志

日本地球惑星科学連合2015年大会　2015/05/24

More details Close

本学学生
デコンボリューションを利用した噴火地震の相対震源決定―ストロンボリ火山への適用―

杉村俊輔, 西村太志, 青山裕, 山田大志, 藤田英輔, 川口亮平, 三輪学央

日本地球惑星科学連合2015年大会　2015/05/24

More details Close

本学学生
蔵王山御釜火口近傍における傾斜観測

日本火山学会2014年秋季大会　2014/11/02

More details Close

本人
繰り返し噴火の規模別頻度分布

西村太志, 井口正人, Muhamad Hendrasto, 青山裕

日本地球惑星科学連合2014年大会　2014/04/28

More details Close

本人
相似地震解析による東北地方太平洋沖地震M9に伴うP波・S波速度の時間変化

Pacheco-vivero Karim, 西村太志, 中原恒

日本地球惑星科学連合2014年大会　2014/04/28

More details Close

本学学生
エンベロープ波形を利用した火山性地震の震源決定法の開発―三宅島B型地震への適用―

内田東, 西村太志, 中原恒, 山里平, 藤田英輔

日本地球惑星科学連合2014年大会　2014/04/28

More details Close

そのほか
Volcano deformations preceding intermittent eruptions from an open conduit International-presentation

AGU Fall Meeting 2008　2008/12
Are there any precursors of the 1998 failed magmatic eruption at Iwate volcano? International-presentation

Sadato Ueki, Satoru Tanaka, Satoshi Miura, Minemori Sato, Haruhisa Nakamichi, Hiroyuki Hamaguchi

AGU fall meeting 2008　2008/12
Response of the Onikobe geyser to the 2008 Iwate Miyagi earthquake International-presentation

Nishimura, T, Ueki, S, Ichihara, M

ASC General Assembly and SSJ Fall Meeting 2008　2008/11
Magma Ascent and Volcano Deformation International-presentation

Asian International Symposium on Modeling of Volcanic Eruption for Volcanic Hazard Assesment　2008/11
2008年岩手・宮城内陸地震の鬼首間欠泉への影響

西村太志, 植木貞人, 市原美恵

日本火山学会秋季大会　2008/10
開口型火道内マグマ上昇と地殻変動

日本地球惑星科学連合2008年大会　2008/05
遠地Pコーダ波3成分エンベロープの特徴とその地域性

日本地震学会秋季大会　2007/10
Modeling of volcanic conduit pressurization due to gas bubbles in basaltic magma International-presentation

IUGG　2007/07
間欠泉活動の複雑性とその要因―宮城県鬼首間欠泉の解析―

西村太志, 植木貞人, 市原美恵

地球惑星科学連合大会　2007/05
マグマ内揮発性成分の挙動による火道の増圧過程

地球惑星科学関連学会　2007/05
Periodic Oscillations observed in the Onikobe geyser, Japan International-presentation

Minemori Sato, Sadato Ueki, Youichi Shimomura, Mie Ichihara

American Geophysical Union　2004/12/13
鬼首間欠泉のメカニズム

佐藤峰司, 植木貞人, 下村陽一, 市原美恵

日本火山学会2004年秋季大会　2004/10/19

Show all Show first 5

Research Projects 32

Study on dynamics of Earthquake Fault Competitive

1992/04 - Present
Study on Source Process of Volcanic Earthquakes Competitive

1992/04 - Present
超高密度多点地震観測と高精度映像分析による爆発的噴火ダイナミクスの解明

西村太志, 中原恒, 田口貴美子, 中道治久, 村田健史, 長妻努, 小園誠史, 江本賢太郎

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 基盤研究(B)

Institution: 東北大学

2022/04/01 - 2025/03/31
地盤表層域における熱水放出の状態変化に関する実験観測的研究

青山裕, 西村太志, 田中良

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 挑戦的研究(萌芽)

Institution: 北海道大学

2021/07/09 - 2024/03/31

More details Close

初年度である2021年度は，北海道南部のしかべ間歇泉で本研究課題の開始前から実施している多項目連続観測を継続して噴出孔内の映像撮影や圧力測定を試みたほか，鬼首間歇泉で取得した熱赤外カメラ及び空気振動観測のデータ解析，霧島硫黄山の噴気観測，地下構造の深部からの熱水供給率を変化させたときの熱水流動の応答に関する数値計算などを実施した．しかべ間歇泉では，間歇泉噴出孔の保守業者の厚意により，6月および9月の作業時に業者所有の孔内撮影用カメラを間歇泉内に挿入し，孔内の状況把握や孔底深度の計測，噴出時の気泡発生状況の動画撮影等を行った．この調査により，掘削深度は約27mであり，ケーシング部分は上部の20mで下部の約7mは裸孔となっていることが始めて確認された．また，井戸の下端には熱水溜まりのような空洞は存在せず，ケーシング下端や裸孔部分の亀裂から井戸内に高温水が流入していることが明らかになった．1月には研究費で購入した圧力センサーを用いて噴出中の孔内圧力を測定し，噴出サイクルを通した井戸内圧力の時系列データを取得した．この調査時には，噴出ごとの熱水噴出体積の推定を試み，過去に見積もられた400L程度であることを確認した．鬼首間歇泉では，間欠泉噴出時に観測した熱赤外映像および空気振動観測のデータ解析を進めた．熱赤外映像は時間的な差分を取ることで短周期変動を強調し，熱水の上方への噴出を調べた結果，周期1秒以下の調和振動が見られることを見出した．空気振動にも同様の振動が見られることから，噴出孔の極浅部で共鳴現象が起きていることが示唆された．宮崎県の霧島硫黄山では，自然の噴気について熱赤外映像の試験観測を行った．予備的な解析では，連続的な蒸気を噴出する噴気にも調和振動的な振る舞いが認められることから，間歇泉現象や噴気現象には浅部に共鳴現象を励起する類似のプロセスがあることが示唆された．
Development of small strain meter for volcano observation

Nishimura Takeshi

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Challenging Exploratory Research

Institution: Tohoku University

2016/04/01 - 2019/03/31

More details Close

We developed a strain meter that can be installed close to a crater of active volcano. The strain meter consists of strain gages and stainless bar, and it is designed by using FEM numerical code to examine the sensitivity. We installed the strain meter at a depth of 20 m of the volcano flank of Sakurajima where volcanic explosions introducing volcano deformation are often observed. The strain signals are continuously recorded with a sampling frequency of 100 Hz at the site. The volcano deformations with a time scale of a few hours were not well observed with a good signal to noise ratio, but short-period seismic waves with amplitudes of about 0.5 micro strain are well recorded.
Study on seismic wave propagation through the heterogeneous structure and the Green function retrieval from the noise cross correlation

SATO Haruo, NISHIMURA Takeshi

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (C)

Institution: Tohoku University

2012/04/01 - 2015/03/31

More details Close

In order to describe the propagation of seismic wave-energy through random heterogeneities of the solid earth medium, we have improved the radiative transfer theory. If we imagine a fractal distribution of scatterers, we can explain the power-law decay of the maximum amplitude and coda amplitude with lapse time increasing. Since low-velocity bodies including melt/or water are expected beneath volcanoes, we have developed the radiative transfer theory which deals with the trap and release of wave energy due to resonant scattering. For the Green function retrieval from the cross-correlation function of ambient noise for the existence of an obstacle (heterogeneity) of arbitrary shape, we have theoretically shown that the generalized optical theorem as the necessary condition.
A study on stress sensitivity of seismic velocity at shallow media using the earth tide and seismic wave interferometry

NISHIMURA Takeshi, TANAKA Sachiko, OHTA Yusaku, NAKAHARA Hisashi

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Challenging Exploratory Research

Institution: Tohoku University

2012/04/01 - 2014/03/31

More details Close

We used the tidal effect acting on the solid earth by the moon to examine the strain sensitivity of seismic velocity at shallow structure. We retrieved seismic waves propagating between two sites by cross-correlating the ambient noises for the dilatational and contractional episodes of the earth tide, respectively. Travel time differences of the seismic waves for the two episodes are measured for the ambient noises recorded at a small seismic array deployed on the foot of Mt. Iwate and Hi-net data. The results show that the seismic velocity at the dilatational episode is slightly lower than that at the contractional one. The strain sensitivity is estimated to be about 2-7x10^4 /strain.
Modeling of volcano inflation associated with magma ascent in an open conduit

NISHIMURA Takeshi

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (C)

Institution: Tohoku University

2009 - 2011

More details Close

Volcano inflations generated by ascent of magma with gas bubbles are investigated. Ascent of magma with gas bubble growth due to diffusive flow causes volcano inflation with a constant rate or temporally accelerated change. For the case of a large slug rising up in viscous melt, volcano inflation turns to deflate when the slug approaches to the ground surface. Finite element calculations indicate that the volcano inflation rate becomes small after the magma head goes above a geodetic station.
Quantification of the crust and mantle heterogeneity and construction of a simulation model for broadband strong ground motions

FURUMURA Takashi, NISHIMURA Takeshi, NISHIDA Kiwamu

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (C)

Institution: The University of Tokyo

2008 - 2010

More details Close

In this study we quantified the crust and mantle heterogeneity, and constructed a broadband strong ground motion simulation model. The distribution characteristic of the small-scale heterogeneities of the scale several kilometers or less in the subsurface structure is evaluated based the analysis of regional seismograms obtained by the Hi-net high-density seismic network from two points : 1) frequency dependency and the distance dependence of collapse of the apparent S-wave radiation pattern and 2) relative strength of the P-wave amplitude in the Transverse component. We developped a high-performance broadband simulation model and large scale simulation was conducted using the Earth Simulator supercomputer.
Field experiments of MOVE for the construction of robot system for volcano observation

TANIGUCHI Hiromitsu, GOTO Akio, UEKI Sadato, NAGATANI Keisi, KANEKO Katsuya, NISHIMURA Takeshi, OSHIMA Hiromitsu, ICHIHARA Mie, SAIKI Kazuto

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (B)

Institution: Tohoku University

2007 - 2009

More details Close

We are aiming at the development of the robotic system that can observe the volcano by wireless control in a near future. For that purpose, we developed MOVE (Mobile Observatory for Volcanic Explosions) based on Grant-in-Aid for Scientific Research on Priority Areas "Volcanic Explosion" that had ended in 2002 fiscal year. This MOVE is improved in the present study for the achievement of the robotic system. In addition, we tried to clarify various problems for development and the solutions based on the field experiment of MOVE. The vegetation and geographical barriers became the troubles when MOVE was used on an actual volcano, and the problem occurred in the wireless control. To avoid this, the base station vehicle was produced in the present study. The wireless machine and the extensible antenna, etc. were installed in the base station car. Next, we selected the volcanoes they were able to be applied actually. The selection was judged based on the possibility of volcanic eruption and the absence of trouble in wireless control. The trouble to the wireless was judged by the examination using the geographical software (KASHMIR) and the site investigation. As a result, two volcanoes (the Aso volcano and the Oshima volcano) were selected for the field experiment. Running and observation experiments in the field were performed twice (March and October, 2009) at these two volcanoes. In these experiments, the wireless control became possible by moving the base station at the points where the wireless control was impossible in the experiment before. As a result, the transport of MOVE from a point parting at about 2km to the summit crater succeeded by the wireless control at the Aso volcano and the Miharayama volcano. Moreover, at the Miharayama experiment, we exchanged the information with the robot researcher in a different field like the engineering system etc. and obtained useful information for the robotic system construction in the future. However, to use the robotic system for the progress in science and disaster prevention, it was clarified that a lot of problems were left such as an increase in the capital, the number of researchers and the construction of operation organization.
高ダイナミックレンジ傾斜センサーによる3成分広帯域地震計の開発

西村太志, 山本希

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 萌芽研究

Institution: 東北大学

2008 - 2008

More details Close

神綱電機社製傾斜角センサーKLSSP-90は, 地球潮汐のような微小な傾斜変動や地震に伴う加速度を記録できることが報告されている. この傾斜角センサーは0-90度までの傾斜角を測定できることから, このセンサー3台をhomogeneous triaxial arrangement(水平面から35.3度傾斜させ, 水平方向に120度ごとに設置)すると3成分の地震計としても利用できる可能性がある. そこで本研究は, この傾斜角センサーの性能を調べた. 個々の傾斜角センサーの特性差を調べるため, 4つのセンサーを東北大学地震・噴火予知研究センターの青葉山観測壕に据え付けた. 4台のセンサーの出力信号を比較した結果, 以下のことが明かとなった. 出力振幅は, 1秒以下の長周期帯では1%以内, 0.1秒付近では5-10%以内で一致する. 位相差は5度以内で一致する. 続いて, 現在広く利用されているストレカイゼン社の広帯域地震計STS-2型地震計と比較を行った. その結果, 傾斜計の出力信号(加速度)を1回数値積分した記録は, 広帯域地震計の速度波形記録と極めてよい一致した. また, 傾斜角センサーをhomogeneous triaxial arrangementで設置し, 上下・水平動の3成分を数値的に合成した結果, STS-2型地震計3成分記録と振幅, 位相ともよい一致が見られた. ただし, 傾斜計の感度は, 1秒から10秒程度の周期帯は, 広帯域地震計に比べて1桁程度, それ以上短周期側では2桁程度検知能力が落ちていくことがわかった. 以上から, 微小地震計としてではなく, 1Gまでの強震計記録として利用することができるといえる.
Study on the non-uniform and non-isotropic inhomogeneous structure of the lithosphere by using short-period seismic waves

SATO Haruo, YAMAMOTO Mare, NISHIMURA Takeshi

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (C)

Institution: Tohoku University

2007 - 2008
マグマ内揮発性物質による火道内部の増圧過程の解明

西村太志, 吉田武義, 中村美千彦, 伊藤高敏, 中嶋悟, 寅丸敦志

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 特定領域研究

Institution: 東北大学

2002 - 2006

More details Close

本研究は,火山爆発の発生前のマグマの状態と爆発的噴火プロセスの関係を明らかにすることを目的とし,これら爆発的噴火の準備に関する一連のプロセスを,発泡過程,脱ガス過程,火道開口・閉塞過程などの素過程に分解し,主に,実験的,理論的な研究を進めた.また,これらの過程を統合したモデルの構築や,噴出物の複数解析や他現象との比較検討に基づき,火道内の増圧過程やマグマプロセスを調べた.脱ガス過程について,主に室内実験の結果から以下のことが明らかとなった.マグマ内に剪断破壊により生じた通路や気泡連結による通路が生じている場合,浸透脱ガス流とともに気泡吸収がマグマ内で生じ,マグマ内に気泡の無い層を形成する可能性がある.また,発泡が十分進んでいない深い領域でも,剪断応力が大きい火道壁近傍などでは気泡が十分連結するため,脱ガスが進行することがある.火道や亀裂の閉塞過程の実験によって,高温マグマの貫入時には熱により周辺岩体が大きく変形し通路を閉塞することがあること,火山下の熱水流動による火山ガラスの水和・変質・溶脱過程により火山体を構成する媒質の浸透率が3桁以上変化すること,が明らかとなった.また,カルデラ崩壊とプルトン貫入の関係をもとに,カルデラの火道形成過程を考察した.マグマ上昇モデルの数値計算から,爆発的噴火前には,マグマが浅部に近づくにつれ揮発性物質の発泡によるマグマの体積増のため地殻変動が急速に進行するのに対し,非爆発的噴火の前には,脱ガスによるマグマ体積の減少が起こるため,急速な地殻変動は観測されないことが明らかとなった.火山噴出物解析を行い,火山灰の火山ガラスの特徴と,地震観測等の力学的条件から区別される桜島の爆発的噴火様式の関係を調べた.また,火山噴出物の水の実効的な拡散係数,色変化特性,浸透率測定から,発泡のその場観測などからマグマ上昇過程に関連した時間スケールを議論した.
Dynamics of Volcanic Explosion

IDA Yoshiaki, TANAKA Yoshukazu, NISHIMURA Takeshi, KOYAGUCHI Takehiro, TANIGUCHI Hiromitsu, OKADA Hiromu

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research on Priority Areas

2002 - 2006

More details Close

This project aims at better understanding of fundamental processes and mechanisms of volcanic explosions with some contribution to volcanic hazard mitigation. The "Mobile Observatory for Volcanic Explosions" that can be moved and operated for observations, sampling and device installation in the vicinity of volcanic craters with a remote control has been developed for detailed studies of volcanic eruptions. New data sets of broad-band seismograms and air-wave records obtained at some volcanoes involving frequent small explosions have revealed the presence of characteristic inflation and deflation prior to each explosion as a common physical process. Theoretical and experimental studies on volcanic materials have specified the factors that may control degassing and fragmentation of ascending magma. Computer simulations about magma ascent processes have clarified the conditions that may determine explosiveness of eruptions and have shown that the explosiveness can be predicted by accelerated inflation. A three-dimensional simulation scheme of effusing gassy flow mixed with magma fragments has been developed to describe volcanic plumes and pyroclastic flows. Scaling of explosions and simulation of explosive air flow also provide useful methods to evaluate influences of volcanic explosions. Compiling our research outcomes and some other knowledge, a database, which is useful for a systematic understanding of volcanic explosions, has been constructed. This database and some computer programs developed in this project can be basic tools in simulating the entire eruptive processes and evaluating possible volcanic hazards. A web server also has been developed for prompt decisions to derive from efficient discussions at volcanic crises. Some lectures about volcanic explosions for the public were given with some demonstration of our studies. A textbook that may explain our research results to the general people will be published.
OBSERVATIONAL RESEARCH ON CRUSTAL STRUCTURE AROUND M6.1 EARTHQUAKE FAULT

NISHIMURA Takeshi, NAKAHARA Hisashi, TANAKA Satoru, SATO Haruo, NAKAMURA Ayako, YAMAMOTO Hidekazu

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (B)

Institution: Tohoku University

2001 - 2003

More details Close

We investigate temporal changes of crustal structure around the 1998 M6.1 earthquake occurred south west of Volcano Iwate by analyzing seismic signals excited by artificial seismic experiments from 1998 to 2003 and by analyzing seismic waves of earthquake families occurring on the Pacific plate boundary. The seismic signals excited by the active shots were recorded by short period and broad band seismometers installed at permanent stations (GNB, ANS, AKM) of Tohoku University and a temporal station (MTI). We estimate phase difference of nearby two seismograms for the six shots by using a cross spectrum method. Then, we evaluate the seismic velocity changes of the structure during the two shots. The results show that the seismic velocity decreases about 1.5% at MTI and GNB stations, which are located at the northern edges of the fault, for shot 1 and shot 2, during which the M6.1 earthquake occurred. Then, the seismic velocity increases of about 0-0.5% is observed for the data from 1998 (after the M6.1 eq.) to 2002. From 2002 to 2003, about 0.3% velocity increase is observed again. Cross-correlation analyses of the earthquake families also show a significant temporal change of heterogeneity around the M6.1 earthquake and Volcano Iwate. We infer that these changes in shallow that are observed from 1998 to 2002 are related to stress release and accumulation of the M6.1 earthquakes and/or structure changes due to the intense volcanic activity of Mt Iwate at this period. We further determined a three-dimensional P-wave velocity structure around the M6.1 earthquake and the spatial distribution of slip and high-frequency wave radiation zone for the M6.1 earthquakes.
Establishment of the scaling rule for explosive eruption and its application to the estimation of hazard distribution

TANIGUCHI Hiromitsu, MIYAMOTO Tsuyoshi, GOTO Akio, NISHIMURA Takeshi, OSHIMA Hiromitsu, HAYASHI Shintaro

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (B)

Institution: TOHOKU UNIVERSITY

2001 - 2002

More details Close

This research work intends to establish the scaling rule that relates the explosion energy and depth of volcanic explosion to the extension and strength of volcanic disaster such as volcanic blast wave, pyroclastic surge and ballistic fragment. For this purpose, we made some field explosion experiments under both of the conditions on the dry ground and in water. These two years we have concentrated on the underwater experiment for getting the understanding of submarine eruption. The main points of observation accompanied to the experiments are as follows : 1.Observation of underwater pressure waves using blast-sensor and underwater microphone 2.Observation of shock wave in the air using blast sensor and high-speed video recorder 3.Observations of water-dome and ballistic fragment usnig visible and infra-red video recorders 4.Simultaneous recording of eqrthquake, air wave and visible image of the explosion The weigh of explosives used (Kiri-dynamite) were ranged from 250g to 4000g, adn the scaled depth ranged from 0 to 2.15 m/g^1/3. Based on these experiments, weconvinced that the scaling rule for underwater volcanic eruption could be also establishd as in the case on dry ground.
STUDY ON SOURCE PROCESS OF VERY LONG PERIOD SEISMIC EVENTS

NISHIMURA Takeshi

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (C)

Institution: TOHOKU UNIVERSITY

1999 - 2000

More details Close

I studied source process of very long period seismic events that have recently been observed at many active volcanoes. I deployed four to six broad band seismometers and a low-frequency microphone around Mounts Iwate and Bandai, northeastern Japan. The two volcanoes have recently shown significant crustal deformations and/or micro earthquake activities, so I successfully recorded high quality data of very long period seismic events of the two volcanoes. Examining the observed waveform characteristics, I determined the locations and space-time functions of moment tensors of the seismic source that excites long period signals of about 10 s. The results show that : (1) the sources for Mount Iwate events are located in a region having a high Vp/Vs ratio that indicates an existence of magmatic fluid ; (2) the source mechanisms of very long period events observed at both of the two volcanoes indicate mutual inflation and deflation motions. Such source mechanisms are also reported for the very long period seismic events at other active volcanoes such as Mount Aso. I, therefore, conclude that the source mechanisms of very long period events includes significant volumetric changes. To explain the observed source mechanisms and the dominant periods of the oscillations, I presented a source model in which compressible fluid motions in an irregular dike or volcanic pipe are expressed by the basic equations for a one-dimensional fluid dynamics. Calculations of the motions using a finite difference method indicate that two chambers connected by a narrow channel can act as an inflation and deflation seismic source. The long period waves of 10 s are easily excited by narrowing the channel without unrealistic large magma chambers and/or magmatic fluid having extremely low acoustic velocity. Based on my analyses of the observed waveforms and theoretical considerations, I conclude that the very long period seismic events are excited by a migration of magmatic fluid in volcanic dikes or pipes with an irregular shape.
Development of the measurement-system of volcanic shock wave both in the air and in the water

TANIGUCHI Hiromitsu, OHBA Tsukasa, NISHIMURA Takeshi, OSHIMA Hiromitsu, MIYAMOTO Tsuyoshi, GOTO Aiko

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (B).

Institution: Tohoku University

1998 - 2000

More details Close

Main purpose of this project is to make a system for volcanic blast wave measurement both in the air and in the water, and to determine the explosion energy and depth of explosive eruption. The ability of the system is as follows : 1. Sampling rate : 〜200 kHz 2. Number of data collection : ca. 10000 For making the system, field explosion experiment was needed. Using this chance, we have attempeted to establish the scaling rule which govern the relations among explosion energy, explosion depth and surface phenomenon of volcanic explosion such as the crater formation and ejection of ballistic fragment. On 31 March 2000, Usu volcano in Hokkaido, Japan, erupted after 22 years dormancy, and it was characterized by numerous numbers of small-scale phreatic explosion. We have attacked to determine the energy and the depth of Usu eruption based on the observations and the scaling rule. These results indicated that the experimental eqtuations obtained in the field experiment relating the explosion energy and depth to the explosion phenomenon explained well quantitatively the real phenomenon at Usu phreatic explosion. The representative explosion energy observed ranged from 10^10 J to l0^12 J, and the representative depth ranged from almost crater surface to about 30 m deep.
STUDY ON REMOTE TRIGGERING MECHANISMS OF MICRO-EARTHQUAKES AT GEOTHERMAL AREAS

OHTAKE Masakazu, NAKAHARA Hisashi, NISHIMURA Takeshi, SATO Haruo

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (C)

Institution: TOHOKU UNIVERSITY

1997 - 1999

More details Close

We studied the remote triggering mechanism of micro-earthquakes based on analyses of the seismic data obtained at geothermal areas. We started a high resolution seismic observation at the Kakkonda geothermal area, Iwate Prefecture, Japan, in May 1998 by using a bore-hole seismometer. However, the Kakkonda area were severely damaged by the M6.1 earthquake on September 3, 1998, and we could not continue the observation after the earthquake. In this study, therefore, we analyzed : (1) continuous records of a broad-band seismometer that was installed 5 km east of the Kakkonda area, and (2) past records of bore-hole seismometer at Kakkonda that were recorded in 1986-1990, July 1993 and December 1994, (3) remote triggering phenomena reported in the world. We further calculated theoretical dynamic strain, static strain and maximum acceleration associated with a large earthquake. Based on these observations and theoretical studies, we obtained the following results : 1. From the observed relations between seismic magnitude and epicentral distance of the earthquakes that remotely triggered micro-earthquakes, we find that dynamic strain associated with a large earthquake plays a main role to trigger micro-earthquakes, and that dynamic strain of more than 10ィイD1-7ィエD1 is necessary to remotely trigger micro-earthquakes. 2. The earthquake swarms are remotely triggered 0.1-1 hour after the maximum dynamic strain due to a large earthquake. 3. Remote triggering phenomena are often observed at geothermal and volcanic areas. This suggests that an increase of pore pressure of magnetic fluid and hot water in the crust may play an important role in the remote triggering mechanism.
噴火微動の発生過程に関する研究

西村太志

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 奨励研究(A)

Institution: 東北大学

1997 - 1998

More details Close

噴火微動記録は噴火規模や推移を定量的に記述することに有効であり,その発生機構の解明は噴火過程の理解や噴火予知の実現に不可欠である.本研究は,世界各地で記録されている噴火微動の共通の特性を明らかにし,その発生過程を実験的に明らかにするものである.過去の文献から噴火微動の最大振幅,継続時間を調べ,火山構造,マグマ特性,爆発指数,噴火継続時間などとともにデータベースを構築した結果,噴火微動の以下の特長が明らかとなった.(a)噴火微動の強度を表すReduced Displacementは噴出口面積にほぼ比例する.(b)微動の波動エネルギーと噴出物質の力学的エネルギーの比である地震波効率は,割れ目噴火の場合には10^<-2>〜10^<-4>,円形の噴出口からの噴火の場合10^<-4>〜10^<-7>と推定された.(c)噴火微動の振幅は時間的に次のように推移する.Stage I:振幅の漸進的な増大;Stage II:最大振幅の維持;Stage III:振幅の漸進的な減少.Stage Iを顕著に示す微動の多くは,一連の火山活動の中で最初の大噴火に伴われた.Stage IIIは約90%のイベントで確認された.(d)噴火微動の最大振幅から推定されるマグニチュードは,同一の噴出口半径で励起された爆発地震のマグニチュードと比較すると,明らかに小さく,異なる噴出口半径依存を示すことが明らかとなった.次に,数値的な実験を行った.その結果,マグマ性流体が大気中に噴出される際には,噴出に伴うマグマ溜まりの圧力減少に伴い長周期の地震波が励起されるだけでなく,大道やマグマ溜まりの共鳴運動により短周期の地震動が励起されることが明らかとなった.この短周期波動の振幅は,噴火直後に増大し,その後,時間経過とともに減少する.この短周期微動は噴火微動として観測されていると考えられる.
Fundamental Research on Application of Magma Exploration Method

HAMAGUCHI Hiroyuki, SHIMIZU H., TANAKA K., NISHIMURA Takeshi, TANAKA S., UEKI Sadato

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (B)

Institution: Tohoku University

1997 - 1998

More details Close

The knowledge of subsurface structure is indispensable to understand an eruptive mechanism of volcano and to increase reliability of prediction of volcanic prediction We have developed the data logging system with small-size, lightweight and high performance and, in the present study, we applied this system to explore the subsurface structure at Bandai volcano, The research group for seismic exploration of Bandai volcano consisted of 10 national universities and JMA 76 members from the above institutions participated in the present experiment. We deployed 292 temporary unattended seismic stations in and around the volcano within 15 km from the summit and observed seismic waves loin 8 explosions that were fired at 10 minutes interval from 102 till 2 : 12 on October 2,1997. We determined three-dimensional P-wave velocity structure inverted from about 2300 first arrival time data The present results are summarized as follows ; (1) the subsurface velocity beneath Bandai volcano and its neighborhood has a large horizontal velocity contrast. At the elevation of 0.5 km above the sea level, P wave velocity is 5.3 km/s beneath the Numano-taira crater, while it decreases to 2-2.4 km/s in the region between the southern flank of Banadai volcano and lake Inawashire. (2) Narrow high velocity body extending vertically is detected just under the Numano-taira miter. This body is much localized feature, similar to intrusive dyke-like and has horizontal extent less than 2 km. (3) This intrusive body is encircled by the convexities of horseshoe shaped caldera wall associated with the past gigantic eruptions. This suggests that the dyke-like intrusion from depths had worked as source of the past destructive explosions.
断層からの高周波エネルギ輻射インバージョンの研究

佐藤春夫, 西村太志

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 重点領域研究

Institution: 東北大学

1997 - 1997

More details Close

高周波数帯における震源過程の研究は,複雑な断層運動の解明や強震動予測を行う上で重要である.従来,コヒーレントな波形解析に基づくインバージョン法が震源過程の推定に用いられてきたが,1Hz以上の高周波帯への適用は困難であった.しかし,高周波地震波動を不均質な構造の中で散乱された波のインコヒーレントな重ね合わせであると考えることにより,そのエンベローブ(包絡波形)形状はエネルギー輸送理論を用いて精度良く記述される.この考えに基づき,我々はダブルカップル型震源に対するS波エンベローブ・グリーン関数の合成法を開発した.この解は,直達波の附近では震源の輻射パターンを忠実に反映するが,経過時間の増加と共に散乱の効果が強く現れ,球対象輻射の場合の解に漸近する.次にこの解をグリーン関数として用いて,強震記録の波形エンベロープから断層面上におけるエネルギー輻射量の空間分布と観測点のサイト増幅係数を推定するインバージョン手法を提案した.これを1994年三陸はるか沖地震と1995年兵庫県南部地震に適用し,地震断層面上における高周波エネルギー輻射量分布の推定を行った.その結果,高周波エネルギー輻射量分布と,低周波波形インバージョンによる断層面上のすべり量分布とが必ずしも一致しないことがわかった.高周波エネルギーは,その大部分が破壊の急激な成長・停止に伴って輻射されているものと考えられる.
Study of Lava Lake at Nyiragongo Volcano

HAMAGUCHI Hiroyuki, MORITA Yuiti, NISHIMURA Takeshi, TANAKA Satoru, UEKI Sadato

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for Scientific Research (B)

Institution: Tohoku University

1996 - 1997

More details Close

The Nyiragongo volcano in the western rift valley of the East African Rift System had a long-lived lava lake in the summit crater for about 100 years. We reviewed this lava lake actibities based on the old documents and the recent our field observations. Some results of the present study is summarized as follows ; (1) Based on the old documents and our field observations, the temporal variations of lava lake activity in the summit crater are summarized for the last 100 years. (2) Based on the observatin of temporal changes of lava-lake elevation, the average magma supply rate is estimated to be 7,000 kg/day. Total magma suplly is 86 million cubic meters in the period of 1994-1996. (3) the volcanic earthquakes were classified into two types on the basis of their waveform. The seismic activity of the A-type events shows ratherconcentrated features at the depth of about 15 km just beneath the Nyiragongo crater. (4) Whenever volcanic tremors are observed the eruptive activity in the lava-lake has been always reognized by an eye-witness. After the initial episode of eruption in the lava-lake, we observed at least 36 eruptive episodes in 1994 - 1996. We found that there is a dear reverse correlation between the occurrence of the A-type earthquakes at a depth and the lava fountain on the surface of lava lake. This feature can be interpreted by the increase of advective overpressure in the conduit system.
Study of Crustal Activity in the East African Rift Valley

HAMAGUCHI Hiroyuki, ZANA Ndontoni, TANAKA Satoru, MORITA Yuiti, KASAHARA Minoru, TANAKA Kazuo

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for international Scientific Research

Institution: Faculty of Science, Tohoku University

1996 - 1997

More details Close

(1) After the initial episode of eruption of Volcano Nyiragongo, eastern Zaire, we monitored the temporal levnl changes of lava lake in the summit crater by using the electro-optical distance measuring (EDM) deuce. The surface of lava lake elevated 118 meter in the period from August, 1994 to September 1996. The lava volume supplied in this period was 86 mmllion cubic meter. (2) We observed at least 37 eruptive episodes in the period from June, 1994 to February, 1995, during which volcanic tremors were intermittently recorded at the nearby stations. The A-type volcanic earthquakes were located at the depth ranges of 10 - 15km beneath the summit and around the NE flank. We found the reverse correlation between the occurence of earthquake and that of tremors. (3) We summarized the volcanic and seismic activities at the Virunga volcanic area, based on the geophysical, geochemical and geological published data. (4) We cooperated with Kenya Institute of Surveying and mapping and made the GPS networks crossing the Rift Valley at the northern Kenya. We measured the seven locations in 1997 and 1998. (5) We analyzed PKP,S and ScS seismic phases recorded by the GDSN networks in order to clarify the lateral heterogeneity in the mantle ant the core : (A) We found that large positive residuals of ScS-S differential travel times greater than 10 seconds locate 2 % low-velocity regions beneath south and northwest Africa : (B) The geographical pattern of the PKP differential travel time (BC-DF) residuals was found to be a manifestation of degree one heterogeneity in the outermost 100 to 500km of the inner core. The P velocities in the inner core are fast in the quasi-eastern hemisphere with a peak value of +0.29 sec and slow in the quasi-western hemisphere with that of -0.66 sec.
震源パラメータ解析に基づく爆発的噴火の発生条件の推定

西村太志

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 重点領域研究

Institution: 東北大学

1996 - 1996

More details Close

噴火に伴い発生する地震及び微動を調べ,爆発的噴火の発生する条件・環境を支配する物理パラメータを探った。火山物質の放出による反作用の力をモデル化したSingle Forceモデル(Nishimura and Hamaguchi, 1993)に基づき,爆発・非爆発的噴火時に山体に働いた力の大きさと力の継続時間を,時間領域あるいは周波数領域で観測波形と理論波形をフィッティング法し,測定した.その結果,爆発地震時に火山体に働く力の大きさは震源継続時間の自乗に比例し,非爆発地震では震源継続時間が力の大きさによらないことがわかった.地下マグマ溜まりからのマグマ上昇モデルを考察した結果,上昇するマグマの大きさが火山体やマグマの物理特性から決定される臨界サイズより大きいとき爆発地震が発生し,小さいとき非爆発地震が発生することがわかった. 火山灰の放出や激しい溶岩放出時に観測される噴火微動を24の微動を文献データをもとに調査した.その結果,噴火微動の強さを表すReduced Displacementは火口半径の大きさにほぼ比例すること,及び,噴火微動は,指数関数的な振幅の増大,最大振幅の維持,指数関数的な振幅の減少という時系列をたどることがわかった.特に指数関数的な振幅減少は9割を越えるイベントで観測され,振幅の増大は一連の噴火活動の初期や大規模噴火時に観測されている.これらの時間変化の変遷は,火口半径の拡大活動やマグマ物性の変化に関係していると考えられる.
Geophysical Study on Hotspot Volcanisim in African Continent (Summary)

HAMAGUCHI Hiroyuki, AKUMBI M., MAVONGA T., WAFULA M., ZANA N., NISHIMURA Takeshi, MORITA Yuichi, KASAHARA Minoru, ISHII Hiroshi

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for international Scientific Research

Institution: Tohoku University

1995 - 1995

More details Close

Although there are many hotspot volcanoes in the African plate, the Nyiragongo volcano in the eastern Zaire presents the highest potential threat to the local habitants. This potential has been recently much enhanced by (a) the starting volcanic eruptions at Nyiragongo on June 23,1994, and (b) the abnormal increasing population of about 1 million refugee fleeing from Rwanda on the middle of July, 1994. We have installed the seismo-volcanic monitoring systems around the volcano. Based on the instrumental observations, we showed that the seismic swarm activities have been high stages in the period between 1994 and 1996 and that they were located at the NE,NW and SE parts of Nyiragongo volcano. Recently, the number of felt earthquakes increased gradually around the volcanic area. We have continued to monitor the change of lava-lake level in the crater of Nyiragongo since August, 1994. We showed that the level of lava lake has ascending with a constant rate of 28 cm/day until July 1995 and that the supply rate of basaltic magma was estimated to be 2.2x10^5m^3/day. This ascend was stopped around October, 1995. The color of lake water in Kivulake changed at the northern part of the lake since February, 1996, which suggests the existence of submarine volcanic activity on the lake bottom. The above mentioned our observations clearly show that the present volcanic activity of Nyiragongo is still very active stages in all aspects. We also investigated the heterogeneity and anisotropy in the inner core. The heterogeneity in the core was examined by using differential travel times of PKP(BC)-PKP(DF). The geographical pattern of the travel time residuals was found to be a manifestation of degree one heterogeneity in the outermost about 500 km of the inner core. Spherical harmonics analysis showed that the P velocities were fast in the region from 43ﾟ E to 177ﾟ E and slow in the region from 183ﾟ W to 43ﾟ E.Geophysical implications of this pattern are briefly discussed.
地下採石場の陥没に及ぼす地球潮汐のトリガー作用の研究

大竹政和, 西村太志

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 一般研究(C)

Institution: 東北大学

1994 - 1994

More details Close

栃木県宇都宮市郊外の大谷地区の地下には,良質な建設用石材として名が知られる大谷石(おおやいし)の長年の採石の結果,地下に夥しい空洞が残されている.このため,死者,家屋損壊を含む地盤陥没災害が繰り返し発生しているが,過去の陥没事故においては,その発生時刻と地球潮汐との間に高い相関関係が認められた.本研究では,これらの陥没の発生予測及び防災対策に資することを目的として,高精度の地震観測を実施してきた.微小規模の空洞破壊振動(AE)を捕らえ,地球潮汐に起因する応力変化とAEとの関係,AEの規模頻別度分布,波形スペクトルの特徴等を調べている.大谷地区のAE観測は平成6年9月より開始し,現在(平成7年3月)も継続中である.具体的には,大谷石採石場内に固有周波数2Hzの微小地震計を設置し,信号を増幅した後,サンプリング周波数100Hz,分解能14bitでA/D変換し,ノート型パソコンのハードディスクに連続で収録している.観測データは,研究室においてワークステーションに転送される.微小なAE波形記録はワークステーションのグラフィック画面上で拡大され,フィルタリング操作を施すことにより,効率よく地震動や人工的振動と区別し整理している.これまでの観測期間には,20Hzを越える高周波成分を含む,10^<-5>m/s程度の最大振幅,約0.6秒の継続時間を持つAEが観測されている.AEの規模別頻度分布,地球潮汐に起因する応力変化とAEの発生の相関関係等の統計的な解析は,観測終了後(平成7年4月)に行う予定である.
Geophysical Study on Hotspot Volcanisim in African Continent

HAMAGUCHI Hiroyuki, KASEREKA M., SASSA M., AKUMBI M., MAVONGA T., WAFULA M., ZANA N., NISHIMURA T., KASAHARA M., MORITA Y., ISHII H.

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for international Scientific Research

Institution: Faculty of Science, Tohoku University

1992 - 1994

More details Close

(1) We analyzed SmKS and PKP waves recorded by the GDSN in order to survey the lateral heterogeneity in the lower mantle and at the top of the Earth's core. The spherical harmonic analysis revealed that the hemishperical (degree 1) pattern in the heterogeneities predominants at the top of the Earth's outer core and inner core beneath the African continent. (2) We developed the small and low-power data logger with the precise GPS clock. This equipments were applied successfully to the field observations in the volcanic regions in Africa. (3) The Nyiragongo volcano in eastern Zaire presents the highest potential threat to human lives in Goma region, partly because of the abnormal increasing population fleeing from Rwanda and partly because of the lack of mitigation plan by the local government. (4) The recent volcano-magmatic activity of Nyiragongo and Nyamuragira are summarized as follows ; (a) After the initial episode of eruption in the lava-lake, we observed at least 37 eruptive episodes in the period from June, 1994 to February, 1995. The most significant features in the episodic pattern are not only the intermittent appearance of active periods but also the change of their tempo that happened at the middle of December, 1994. Since January, 1995, the intermittency has declined and continuous features of tremors with small amplitudes became predominant, which suggests that dike-like ocnduit changed to the open conduit system. (b) The seismic activity shows rather concentrated features at the depth of about 15 km just beneath the Nyiragongo carter. The earthquakes with very shallow focal depths were not located closely to the Nyiragongo crater. (c) The pattern of continuously recorded tilt vector indicates that Nyiragongo has slowly inflated since the beginning of eruption. This inflation was probably caused by the storage of excess magma in the very shallow reservoir or in the lava lake.
地震波を用いた噴火の力学過程に関する研究

西村太志

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 奨励研究(A)

Institution: 東北大学

1993 - 1993

More details Close

噴火時に火山体に作用する力の大きさFと力の働く時間tauの関係を定量的に明らかにするために、穏やかな噴火により励起される規模の小さい噴火地震から爆発的噴火に伴う爆発地震を解析した。十勝岳,浅間山,セントヘレンズ火山のデータを解析した結果,以下の関係が明らかとなった。(1)爆発地震の震源パラメータの間には,Fはtau^2に比例するという関係が認められた.(2)規模の小さい噴火地震の震源パラメータの間にはtauはFに依存せずにほぼ一定の値をとるという特徴が認められた。これは,爆発地震のスケーリング法則とは明らかに異なる.(3)Single Force Model (Nishimura and Hamaguchi,1993)によると,(1)(2)の結果は,爆発地震を励起するマグマの温度は一定であるのに対し,規模の小さい地震のそれは規模が大きくなるにつれて温度が高くなることに相当する. 規模の小さい地震から大きい地震まで,統一的に解釈できる噴火地震の発生モデルを考案した.これは,まず,火山直下数キロメートルに存在が指摘されているマグマ溜まりから,半径rのマグマ球が,ホットストークス流れと熱伝導による冷却過程を満足しつつ上昇する.そして,地表面に到達したときに噴火地震を励起するというモデルである.数値計算によれば,マグマの物性等で決定される臨界マグマサイズよりも小さいマグマ球は上昇中の冷却によりマグマの温度が下がるのに対し,大きいマグマ球はマグマ溜まりの温度のまま地表面に達する.つまり,マグマのサイズが温度の違いを生じ,異なるタイプの噴火地震を励起しているとかんがえられる. 本研究では,爆発的な噴火と比較的穏やかな噴火は,火口深部から上昇してくるマグマの大きさにより区別されている可能性が高いことを示した.
Broad-band Seismological Observation in the African Continent and Study of the Earth's Deep Interior

HAMAGUCHI Hiroyuki, KASAHARA Minoru, NISHIMURA Takeshi, MORITA Yuichi, UEKI Sadato

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for General Scientific Research (B)

Institution: TOHOKU UNIVERSITY

1991 - 1992

More details Close

This study was divided into two parts. The one is to set-up the broad-band seismometer in Zaire and to observe the regional and teleseismic events. However, this program was interrupted by the social crisis in Zaire that occurred on September 11, 1991. The other is to study the heterogeneity in the mantle and core by using the data of the WWSSN and GDSN. The followings are the brief summary of the present study: (1)The core-mantle boundary (CMB) was bumped several kilometers just beneath the central Africa and the S velocity in the D" layer was 3-5% slower beneath Africa than the standard model. (2)Spherical harmonic analysis of the lateral heterogeneity of the travel time residuals in the outer core indicated that degree 1 component was most dominant (+/-0.3% of P velocity). This could not be explained by lower mantle heterogeneity nor CMB topography. We suggested that adiabatic temperature at CMB were relatively higher beneath the African hemisphere and lower beneath the Pacific hemisphere. (3)Based on the extensive data set of travel times of SmKS (m=1,2,3), new P velocity model (KTH) of the outer core was presented. (4)S velocity in the D" region beneath the Indian Ocean, Central Asia and N.W. Pacific Ocean were 1-2% faster than those of PREM. (5)GPS portable clock with high precision was developed for the field seismometry. The time accuracy was within 1 milli-seconds.
Geophysical Study on the Hotspot Volcanoes in the African Continent.

HAMAGUCHI Hiroyuki, NISHIMURA Takeshi, HAYASHI Shintaro, KAVOTHA K. S., MORITA Yuichi, KASAHARA Minoru, TANAKA Kazuo, WAFULA Mifundu, ZANA Ndontoni

Offer Organization: Japan Society for the Promotion of Science

System: Grants-in-Aid for Scientific Research

Category: Grant-in-Aid for international Scientific Research

Institution: Tohoku University

1990 - 1991

More details Close

This study is divided into two parts : The one is to study the heterogeneity of the deep mantle and the core-mantle boundary beneath the African plate. The other is the geophysical surveys of active hotspot volcano Nyamuragira and Nyiragongo in the western branch of the East African Rift Valley. The field studies in 1990 were successfully carried out in Zaire, however those in 1991 have been interrupted by the social unrest that occurred on September 23, 1991. The followings are the brief summary of the present study. (1) Observation of broad-band seismometer : The broad-band seismometers (CMG-3) were installed at Lwiro seismographic station (LWI), C. R. S. N., Bukavu, Zaire in 1990 and at Binza meteorological station (BNZ), Kinshasa in 1991. However, the seismometer at BNZ have been operated incompletely because the installation was interrupted by the social unrest. It can not be discussed the results for lack of data. We studied the heterogeneity in the mantle and core by using the data of WWSSN and GDSN. The following results were obtained ; (a) the core-mantle boundary was bumped several kilometers just beneath the African continent, (b) the S velocity in the D" layer was 3-5% slower beneath Africa than the standard model such as PREM. (3) The temperatures on the surface of the core was estimated to be several ten mili-kelvin higher in the A-hemisphere including the Africa and Atlantic regions than in the P-hemisphere including the Pacific region. (2) Volcanic earthquake and tremor : In addition to the four seismic stations of C. R. S. N., the eight temporary stations were installed in and around volcano Nyiragongo and Nyamuragira in 1990. A moderate size earthquake occurred at the SE part of Nyiragongo volcano on September 20, 1990, which induced a swarm of small earthquakes at the axis of the rift valley. The low frequency volcanic earthquakes accompanying the strombolian eruption at Nyamuragira volcano were located at the depth of 0.2-0.5 km just beneath the active vent. These events were explained by the downward single forces having 10^4-10^5 Newtons and 0.15 sec pulse width at a source. (3) Crustal movements : The geodetic measurements at eight base lines crossing the caldera rim of Nyamuragira revealed 15-36 cm dilatations during the period of 1989 and 1990. This dilatations were due to the opening of the fissure genarated by the 1989 eruption in the caldera. On the other hand, the geodetic measurements at the base lines crossing the rift valley showed no significant changes, suggesting that the recent crustal movements were limited in the active volcano area. (4) Magma activity : Temporal chemical variations at Nyamuragira were examined on two different time scale ; 1976-1899 (seven eruptions) and 23 days during the 1986 eruption. In both cases, lava has become more mafic with time, indicating that a zoned magma body, with less mafic magma at the top, is being sampled at sequentially greater depths over the course of time. (5) Recent eruption : After two years and one month dormancy, Nyamuragira began to erupt on September 20, 1991 from a fissure with the strike of N30E at about 15 km NE from summit. A swarm of earthquakes for 3 days preceded the eruption by one week. The new cone grew up 60-70 meter high with basal dimension of 400 x 300 meters during a week. It should be concluded, from what has been summarized above, that the present study contributed significantly to understand the intraplate hotspot activity in the African continent.
伊東沖海底の噴火の特性とその予測に関する研究

浜口博之, 西村太志, 森田裕一, 植木貞人

Offer Organization: 日本学術振興会

System: 科学研究費助成事業

Category: 重点領域研究

Institution: 東北大学

1990 - 1990

More details Close

1989年7月13日の伊東沖海底噴火の直後より約100日間伊東市周辺の7ヶ所で実施した観測デ-タから,P,S時間を再験測し,高精度の震源決定をおこなった。群発地震は深さ2km以深の基盤(Vp=5.3〜5.4km/sec)に起きているが,噴火地点(手石海丘)直下のみは,深さ0.5〜2kmの湯ヶ島層群(Vp=2.6〜3.0km/sec)にも地震がしみだすように発生している。この表層は一般に地震を起こし得ない軟らかな地層であるにもかかわらず,噴火地点直下のみに地震が認められることは,マグマの急激な上昇に伴う応力を反映したものであろう。このような地震の震源分布を手石海丘と対比し,地震グル-プBとCの間の空白域が深部マグマ上昇経路を示すものであると結論づけた。また,1930年(昭和5年)の伊東群発地震の読み取り値(Nasu,1933)を再検討し,新しい地殻構造モデルに基づき,震源の再決定をおこなった。この結果,1930年の活動は震央位置は1989年と同一であるが,深さ分布に決定的な差異があることを明らかにした。すなわち,1930年は地震が深さ6〜10kmに分布し,一方,1989年は1〜5kmに分布する。両者の有意な差は水準測量の結果でも認められた。群発地震の深さの差が海底噴火の発生要因を決めている。事後の判断ではあるが,60年前の伊東群発地震は,今回の噴火の前駆的現象であったと結論される。噴火前兆現象が地震計測学的に,このような60年間をはさんで検出されたことは,噴火子知の長期的予測や単成火山の噴火機構を知る上から重要な知見といえる。

Show all Show first 5

Social Activities 24

光ファイバー＆DAS観測

2020年夏の学校

- 2020/09/09
NTTドコモ火山コンソーシアムセミナー「火山現象」

- 2020/08/24
光ファイバ＆DAS観測による地盤構造と震動源モニタリング

・第22回国土セイフティネットシンポジウム「都市の安全を支える強震観測と光ファイバセンシング技術の展望」

2025/02/06 -
模擬講義秋田県湯沢南中学校

2024/10/25 -
防災科研令和6年度成果発表会「国土の安全と防災連携」～一つひとつの大切な”いのち”を守るため～

2024/10/11 -
新たな火山監視技術と噴火予知

学士会夕食会

2024/02/09 -
国⼟交通省の光ファイバケーブルを利⽤したDAS観測事例

第21回国土セイフティネットシンポジウム「光ファイバセンシングによる都市モニタリングの可能性」

2024/02/08 -
火山人材育成霧島フィールド実習

2017/03/17 -
火山人材育成PJについて

2016/09/15 -
市民のためのサイエンス講座2016

2016/09/03 -

More details Close

講演者西村太志講演タイトル火山噴火の謎に迫る～巨大地震と東北の噴火予知～
火山人材育成PJについて

2016/09/01 -

More details Close

取材対応
火山若手の会における講演

2016/08/31 -

More details Close

講演者西村太志講演タイトル地球物理観測によるマグマ特性の把握
大地震による噴火発生について

2016/07/04 -

More details Close

インタビュー）［サイエンスＶｉｅｗ］大地震と噴火関係は？
熊本地震に関する調査

2016/05/30 -
熊本地震に関する調査

2016/04/22 -
宇都宮東高校高大連携「大学講座」

2015/11/20 -

More details Close

講演者：西村太志講演タイトル：「火山噴火のダイナミクス」
免許状更新講習「地球と宇宙の科学」

2015/08/01 -

More details Close

高校教員等に講義
東日本放送夕方ニュース

2014/11/20 -

More details Close

蔵王山について、研究室にてインタビュー
仙台市立仙台青陵中等教育学校一日大学

2012/11/20 -

More details Close

「一日大学」に講師
東北大学サイエンスカフェ

2010/07 -

More details Close

マグマの動きを探知する～火山噴火予知の最前線
出前授業

2005/02/02 -

More details Close

仙台一高において講義
宮城県教育研究センター教職員研修の講師

2004/07/07 -

More details Close

地震・火山活動の講義
宮城県警察機動警ら隊講演

2004/02/16 -

More details Close

火山活動に関する講演
仙台市科学館サイエンスセミナー

2003/02 -

More details Close

講演

Show all Show first 5

Media Coverage 20

火山研究者10年で倍増

毎日新聞　科学の森

2025/02

Type: Newspaper, magazine
次代へつなぐ御嶽山噴火災害10年4

信濃毎日新聞

2024/06

Type: Newspaper, magazine
光ファイバー網で地震計測

日本経済新聞

2024/03/29
危機の記憶岩手山・火山防災の今

河北新報　下専門人材不足

2024/03/23

Type: Newspaper, magazine
光ファイバー網で地震観測

読売新聞

2023/04/30

Type: Newspaper, magazine
予測難しい火山噴火”光ファイバー””火山ガス”高く手法で噴火の前兆をつかめ！

日テレニュース

2023/01/03

Type: Internet
光ケーブル地震計に

読売新聞

2022/11/10

Type: Newspaper, magazine
大地震が噴火誘発「発生後10年ほど2～3倍」

河北新報

2021/09/16

Type: Newspaper, magazine
光ファイバーケーブルとDASを用いた火山地震観測に関する研究

河北新報、日経電子版、OPTRONICS ONLINE オプトロニクスオンライン　https://kahoku.news/articles/20210323khn000030.html, https://www.nikkei.com/article/DGXLRSP607047_S1A320C2000000/, https://optronics-media.com/news/20210322/72587/

2021/03

Type: Newspaper, magazine
火山人材育成コンソーシアム構築事業

中高生のための研究キャリア・サイエンス冊子「someone」vol.53に掲載

2020/12
間欠泉（台風19号の川俣温泉への影響）

日本テレビニュースエブリ

2019/11
火山人材育成コンソーシアム構築事業

日経新聞

2019/09
火山人材育成コンソーシアム構築事業火山学実習（樽前山）の取材

NHK函館

2019/09
火山研究に関する取材

共同通信

2018/11
間欠泉に関する取材

読売新聞

2017/10
火山人材育成のフィールド実習

2017/03

Type: TV or radio program

More details Close

インタビュー、説明
火山噴火前の地震活動について

西日本新聞、共同通信、毎日新聞等

2015/09/25

Type: Newspaper, magazine

More details Close

火山学会発表の紹介
東日本放送夕方ニュース

2015/04

Type: Newspaper, magazine
東北放送「ふしぎのトビラ」

2006/11/11

Type: TV or radio program
東京大学地震研究所サイエンスカフェ火山研究・人材育成に関する説明

マスコミ各社

Show all Show first 5

Other 4

ストロンボリ火山噴火に先行するマグマ上昇過程に関する研究

More details Close

火山の爆発的噴火過程に重要な役割を果たすと考えられているマグマ内揮発性物質の挙動を、イタリア国ストロンボリ火山を対象として、山体変形データと気泡挙動を加味したモデリングの比較を通して、真っ赤な溶岩を爆発的に噴出するストロンボリ式噴火に伴うマグマ上昇・噴出過程を明らかにする。真っ赤な溶岩を間欠的に爆発するストロンボリ式噴火は、世界の多くの低粘性マグマを有する火山で発生する。このストロンボリ式噴火機構は、現在、火道内を大気泡が上昇する「スラグ流モデル」により広く説明されている。しかしながら、最近申請者らが行った理論予測では、スラグ流モデルは、共同研究者であるフィレンツェ大学Ripepe 教授が観測した山体変形データの基本的特徴を説明できない可能性が高い。そこで、スラグ流モデルのほかに、複数の異なるマグマ上昇モデルを検証する目的で、モデルからの山体変形の予測値を加味して臨時の観測点を設置し、噴火に先行して上昇するマグマにより生じる山体変形データを取得する。モデルから予測される山体変形量と観測値を比較することにより、最適のモデルを求め、噴火前のマグマ上昇機構を定量的に明らかにする。さらに、推定されるモデルパラメータを、噴火の継続時間や大きさと比較し、噴火規模を支配するパラメータを明らかにする。
2011年東北地方太平洋沖地震による東日本地域の地殻構造の地震波速度変化と地殻変動

More details Close

本研究は、巨大地震によって引き起こされた東日本の地殻変動と地震波速度変化を、防災科学技術研究所、国土地理院や東北大学の地震波、ＧＰＳ、ＩｎＳＡＲのデータを利用し、精度良く推定することを目的とする。具体的には、日本側は大地震による地殻変動推定，地震波速度変化の要因解明を担当し、フランス側はデータセンター構築と4次元速度変化分布の推定を主に担当する。両国の研究チームが相互補完的に取り組み、得られた成果を比較検討することで、これまでにない地震活動が起きている東北地方の地殻構造の状態を明らかにする。また、その成果は、今後の地震火山活動を評価する上での基礎的な資料となることが期待される。
日本の火山性地震・微動のデータベース
全地球ダイナミクス

More details Close

マントル最上部構造の微細構造の地震学的研究