A5029568238- earthquake and tectonic studies
- Seismology and Earthquake Studies
- Seismic Waves and Analysis
- High-pressure geophysics and materials
- Geological and Geochemical Analysis
- Earthquake Detection and Analysis
- Geophysics and Sensor Technology
- Seismic Imaging and Inversion Techniques
- GNSS positioning and interference
- Landslides and related hazards
- Earthquake and Tsunami Effects
- Geological and Geophysical Studies
- Fire effects on ecosystems
- Earthquake and Disaster Impact Studies
- Anomaly Detection Techniques and Applications
- Wave and Wind Energy Systems
- Methane Hydrates and Related Phenomena
- Human-Automation Interaction and Safety
- Meteorological Phenomena and Simulations
- Marine and environmental studies
- Structural Health Monitoring Techniques
- Gaze Tracking and Assistive Technology
- Geophysics and Gravity Measurements
- Astro and Planetary Science
- Speech and dialogue systems
Association for the Development of Earthquake Prediction
2001-2018
National Research Institute for Earth Science and Disaster Resilience
2006-2010
The University of Tokyo
1998-2001
We report on the very-low-frequency earthquakes occurring in transition zone of subducting plate interface along Nankai subduction southwest Japan. Seismic waves generated by with seismic moment magnitudes 3.1 to 3.5 predominantly show a long period about 20 seconds. The seismicity accompanies and migrates activity deep low-frequency tremors slow slip events. coincidence these three phenomena improves detection characterization earthquakes, which are thought increase stress updip megathrust...
Short‐term slow slip events accompanied by nonvolcanic deep low‐frequency tremors and very low frequency earthquakes in southwest Japan were investigated systematically means of ground tilting studies. The change tilt usually lasts for several days. By using a genetic algorithm least squares method, we inverted the data steps that caused detected at four stations situated near source tremor. Fault parameters estimated 54 episodes occurred mainly western Shikoku, northeastern Kii, Tokai...
We present a 'pseudo-bending' approach to 3-D ray tracing in spherical earth with discontinuities. This method is based on three-point perturbation associated first-order approximation, while Snell's law curvilinear coordinates applied at the demonstrate computational accuracy and efficiency of pseudo-bending rays for various velocity models by comparing results analytical solutions from bending method. The improvement significant, but reduced as number discontinuities increases. Since may...
A recent extensive seismic wide‐angle experiment revealed a new image of crustal and uppermantle structure across Northern Honshu Arc, Japan. The western part the arc recorded deformation by Miocene back spreading Sea crust is composed highly deformed Tertiary sedimentary layers, relatively low velocity (5.75–5.9 km/s) crystalline basement 15‐km thick lower with 6.6–7.0 km/s. Clear westward thinning from 32 to 27 km represents extensional backarc spreading. attains maximum thickness...
Abstract Continuous seismic data and tilt measurements in the Aichi Mie regions of central Japan indicate significant migration episodic non-volcanic deep tremors short-term slow-slip events on subducting plate interface at deeper extension mega-thrust earthquake seismogenic zone. These tremor slip (ETS) occur two concentrated either side Ise Bay recurrence intervals approximately every 6 months throughout 2004 2005, separated by a distinct gap. A migrating episode from southern edge region...
We have elucidated depth variations in the stress field associated with 2007 Noto Hanto, Japan, earthquake by tensor inversion using high-quality aftershock data obtained a dense seismic network.Aftershocks that occurred above 4 km indicated strike-slip regime.By contrast, aftershocks deeper parts thrust faulting regime.This variation regime correlates well slip direction derived from finite source model geodetic data.Furthermore, maximum principal (s 1 ) axis was stably oriented...
Abstract We evaluate response of Mid‐Niigata during the preseismic, coseismic, and postseismic periods 2011 Mw9.0 Tohoku‐oki earthquake by analyzing strain distributions based on a dense Global Positioning System network. Decomposition coseismic E‐W according to its wavelength shows localized elastic extension, while persistent contraction in short‐wavelength component within narrow zone 40‐ 60‐km width is significant before after event, implying persistence an inelastic process. Differences...
We invert shear‐wave waveform data for the radial variation of (isotropic) shear‐velocity in D″ beneath Northern Asia. reduce source and receiver effects by using intermediate deep events Italy Japan recorded respectively at stations East Asia Europe. Relative to PREM, we find a significantly higher S‐wave velocity depth range from 150 300 km above core‐mantle boundary (CMB) slightly lower 0–150 CMB. As our previous studies structure Central America Arctic obtained similar models, suggest...
新潟県中越地域に展開された観測点間隔5 km～10 kmの高密度地震観測網により観測された東北地方太平洋沖地震の記録の分析を行った。加速度波形は、太平洋側の宮城県・福島県とは異なり特徴的なパルスを持つ波群はなく、丘陵部で10～20 cm/s2、平野部で30～40 cm/s2である。加速度フーリエスペクトルは、高周波成分が小さく1 Hz以下の振幅が大きい。また、0.1 Hz以下はほぼ同一でNS成分の0.02 Hz、EW成分及びUD成分の0.04、0.06、0.08 Hzに共通のピークが認められる。0.1～2 Hzのスペクトル振幅は、平野部で周辺丘陵部の約5倍である。速度波形ではEW成分及びUD成分に二つの明瞭なパルスが確認される。最大加速度、最大速度は、丘陵部で小さく平野部で大きく大局的には地形と対応がよく、AVS30との相関も確認できる。ただし、最大速度は既往の知見よりAVS30に対する傾きが小さく低周波数側の影響が示唆される。また、周期5秒、10秒の加速度応答（減衰5%）は、地形よりも地震基盤深さ分布との相関が見られ、厚い堆積層の影響も示唆される。
In 1997, two strong earthquakes occurred on March 26 (M j 6.6) and May 13 6.4) in the northwestern part of Kagoshima Prefecture, Japan (termed 1997 Northwestern Earthquakes).However no seismogenic faults associated with these had previously been recognized at surface.
The parametrized shooting method is extended to 3-D seismic ray tracing in a spherical earth with discontinuities. A vector at source iteratively updated by using numerical integrals of several variables and Snell'ls Law coordinates matched the computational accuracy efficiency this are demonstrated rays for various velocity models comparing results analytical solutions from bending, pseudo-bending finite difference methods. very efficient an smooth field it reduced introduction...