産業技術総合研究所 活断層・火山研究部門
Seismotectonics Research Group, Research Institute of Earthquake and Volcano Geology, GSJ / AIST


ユトレヒト大学大学院生 Milo Trainor Moss氏が技術研修で10月まで滞在します。
Mr. Milo Trainor Moss, a graduate student of Utrecht University, has arrived and works on his research until October as a technical trainee.
New publication.
Effects of frictional properties of quartz and feldspar in the crust on the depth extent of the seismogenic zone
Koji Masuda, Takashi Arai, Miki Takahashi
Progress in Earth and Planetary Science 6:50, (IF=2.676)

We measured the frictional properties of quartz and feldspar, two of the major components of crustal rocks, under subsurface pressure and temperature conditions characteristic of the depths at which earthquakes occur. In the presence of water, the temperature range over which the velocity dependence of steady-state friction was negative was wider for feldspar than for quartz. Our results showed that feldspar probably plays a more important role than quartz in determining the depth extent of the seismogenic zone.
We had exhibitions at AIST open house on July 20.
産総研一般公開 AIST Open House
The crustal stress map of the Kanto region was published.
今西和俊・内出崇彦大谷真紀子松下レイケン中井未里,関東地域の地殻内応力マップ,地質調査研究報告,第70巻,第3号,p. 273–298, 2019
Kazutoshi Imanishi, Takahiko Uchide, Makiko Ohtani, Reiken Matsushita and Misato Nakai (2019) Construction of the Crustal Stress Map in the Kanto Region, central Japan. Bull. Geol. Surv. Japan, vol. 70 (3), p.273–298.
GeoProc2019(7月3日-5日 オランダ ユトレヒト)に参加しました.(高橋,Verberne)
Takahashi and Verberne have attended GeoProc2019 in Utrecht, the Netherlands on July 3-5.
奥脇 亮 JSPS特別研究員が筑波大学山岳科学センターに異動いたしました.
Ryo Okuwaki, JSPS postdoctorial researcher, has moved to Mountain Science Center, University of Tsukuba.
New publications.
Synchronization of megathrust earthquakes to periodic slow slip events in a single-degree-of-freedom spring-slider model
Ohtani, M., N. Kame, and M. Nakatani
Scientific Reports, 9, 8285, DOI: 10.1038/s41598-019-44684-4 (IF=4.122)

周期的に発生する長期的スロースリップ(SSE)が,近くの大地震の発生タイミングに及ぼす影響を一自由度モデルで調べました. 地震の発生タイミングがSSEのリズムに支配され、地震周期がSSE周期に引き込まれる、同期現象というおもしろい現象が起こりました.
We investigated the effect of periodically repeating long-term slow slip events (SSE) to the timing of an earthquake in the neighbor using a spring-slider model. The period of an earthquake is entrained to that of SSE; i.e., synchronization occurred. Surprisingly, the timing of an earthquake is controlled by the rhythm of SSEs, rather than the toughness of the fault.
Seismic potential around the 2018 Hokkaido Eastern Iburi earthquake assessed considering the viscoelastic relaxation
Ohtani, M. and K. Imanishi
Earth, Planets and Space, 71, DOI: 10.1186/s40623-019-1036-4 (IF=2.773)

We assessed the seismic potential on the faults in the eastern boundary fault zone of the Ishikari low-land after the 2018 Hokkaido Eastern Iburi earthquake. We derived the stress field around the targeted faults and calculated the Coulomb stress change considering viscoelastic relaxation after the Iburi earthquake. The results suggest that the target faults are in the state of increasing seismic risk after the Iburi earthquake.
Nucleation of characteristic earthquakes in simulated cycles Involving deep huge slow slip events
Ohtani, M., N. Kame, and M. Nakatani
Journal of Geophysical Research: Solid Earth, 124, 2, 1822-1837, DOI: 10.1029/2018JB016156 (IF=3.48)

Precursory large slow slip event (SSE) may have occurred just before the 1946 Showa Nankai earthquake. We simultaneously modeled the megathrust earthquake and the deep SSE. The simulation results showed three patterns of nucleation processes, and a large SSE does not necessarily trigger an immediate earthquake.
New publications.
Nanocrystalline principal slip zones and their role in controlling crustal fault rheology.
Verberne, B.A., Plümper, O., and Spiers, C. J.
Minerals 9, 328, (IF=1.835)

In this review paper we highlight the importance of nanogranular rock within crustal fault zones. It appears these particles are widespread in the crust, and that they are characterized by anomalous physical behaviour. Nanograins may play a key role in natural earthquake cycles.
Frictional properties of simulated chlorite gouge at hydrothermal conditions: Implications for subduction megathrusts
Okamoto, A., Verberne, B. A., Niemeijer, A. R., Takahashi, M., Shimizu, I., Ueda, T., and Spiers, C. J.
Journal of Geophysical Research: Solid Earth, (2019) (IF=3.482)

We tested the frictional properties of chlorite under conditions simulating subduction fault slip. The results provide valuable input to future and existing models for subduction zone earthquakes, such as those nucleating below southwest Japan.
Inelastic deformation of the Slochteren sandstone: Stress‐strain relations and implications for induced seismicity in the Groningen gas field.
Pijnenburg, R. P. J., Verberne, B. A. , Hangx, S. J. T., and Spiers, C. J.
Journal of Geophysical Research: Solid Earth 122, (IF=3.482)

We investigated pore-pressure depletion-induced compaction of sandstone, demonstrating that inelastic deformation is crucial at low strains. The results have important implications for geomechanical models describing pore-pressure depletion-induced reservoir compaction, subsidence, and seismicity.


地震テクトニクス  地震テクトニクス研究グループでは,地震観測・解析,過去深部にあった断層帯の地質調査,室内岩石実験,数値シミュレーション,などの研究を有機的に連携させて,地震が発生する場や発生にいたるプロセスを解明する研究に取り組んでいます.
seismotectonics  Our group aims to elucidate the physical and mechanical properties of the seismogenic zone, and the generation processes of large earthquakes, by linking seismological observations and data analysis, geological studies of exhumed faults, laboratory experiments, and numerical modelings.
 We have published the seismotectonic map of the Kanto region, and are currently constructing a seismotectonic map of the Chugoku region (SW Japan) based on detailed knowledge of local stress fields. We also aim to accelerate seismic data processing in order to complete seismotectonic maps for all regions of Japan. Furthermore, we are studying the deformation processes operating within fault rocks under conditions spanning the brittle to ductile regimes, and we are developing simulation techniques by integrating the interaction between subduction-zone - and inland earthquakes.
 Our studies provide a basis for improving accuracies of long-term forecasting and evaluation of the magnitudes of future earthquakes.