A5054157480- earthquake and tectonic studies
- Seismology and Earthquake Studies
- Seismic Waves and Analysis
- Seismic Imaging and Inversion Techniques
- Methane Hydrates and Related Phenomena
- High-pressure geophysics and materials
- Geological and Geochemical Analysis
- Geological and Geophysical Studies
- Earthquake Detection and Analysis
- Underwater Acoustics Research
- Geophysics and Sensor Technology
- Underwater Vehicles and Communication Systems
- Geophysics and Gravity Measurements
- Drilling and Well Engineering
- Earthquake and Disaster Impact Studies
- Geophysical and Geoelectrical Methods
- Ionosphere and magnetosphere dynamics
- Geological Studies and Exploration
- Geological Modeling and Analysis
- Earthquake and Tsunami Effects
- Inertial Sensor and Navigation
- Advanced Computational Techniques and Applications
- Reservoir Engineering and Simulation Methods
- Oceanographic and Atmospheric Processes
- Hydraulic Fracturing and Reservoir Analysis
The University of Tokyo
2016-2025
Association for the Development of Earthquake Prediction
2016-2025
Hakodate Central General Hospital
2025
Earthquake Engineering Research Institute
2015-2024
Japan Agency for Marine-Earth Science and Technology
2023
National Research Institute for Earth Science and Disaster Resilience
2020-2023
Kyoto University
2023
Ministry of Agriculture and Forestry and Food
2023
Japan Meteorological Agency
2007-2022
National Institute of Technology, Maizuru College
2012-2014
Detection of the presence melt at variable depth beneath two oceanic plates reveals vertical extent old plates.
Tsunami waveform inversion for the 11 March, 2011, off Pacific coast of Tohoku Earthquake (M 9.0) indicates that source largest tsunami was located near axis Japan trench. Ocean-bottom pressure, and GPS wave, gauges recorded two-step waveforms: a gradual increase sea level (~2 m) followed by an impulsive wave (3 to 5 m). The slip distribution estimated from 33 coastal tide gauges, offshore bottom-pressure show large slip, more than 40 m, along trench axis. This similar but much larger 1896...
Abstract The 2024 Noto-Hanto earthquake with a magnitude of 7.6 occurred in the Noto Peninsula on January 1, 2024. mainshock had reverse fault focal solution and direction compression axis was northwest–southeast. In Peninsula, swarms have been observed since December 2020. contrast to this swarm activity, extending marine area. Therefore, we performed rapid response seafloor seismic observation source region its vicinity. We deployed 34 free-fall pop-up type ocean bottom seismometers (OBSs)...
A detailed structural model of the crust, subducting slab, and underlying upper mantle across northern Izu-Ogasawara (Bonin) island arc system is derived from a marine seismic reflection ocean bottom seismographic refraction survey subsequent forward modeling combined with tomographic inversion. The indicates that crust thickest beneath presently active rift zone granitic may have formed in mid-crust. highly attenuative (that is, one low quality Q ) seems to be confined mainly zone. In...
The 2011 Tohoku Earthquake caused a devastating tsunami along the shoreline from to Kanto districts. Although many of tide gauge stations coast were saturated or damaged due tsunami, two cabled ocean-bottom sensors installed off Kamaishi successfully recorded waveform just above source rupture area. records indicated characteristic two-stage development sequence: smoothly increasing amplitude 0 2 m during first 800 s earthquake origin time, and short-period impulsive with peak more than 5 in...
Subducting seamounts are thought to increase the normal stress between subducting and overriding plates. However, recent seismic surveys laboratory experiments suggest that interplate coupling is weak. A survey in Japan Trench shows a large seamount being subducted near region of repeating earthquakes magnitude M ∼ 7. Both observed seismicity pattern rupture propagation during 1982 7.0 event imply was weak over seamount. area with small slip occurred front Its northern bound could be...
[1] The 2011 Tohoku earthquake was observed by dense strong motion, teleseismic, geodetic, and tsunami networks. We first inverted each of the datasets obtained networks separately, for rupture process earthquake. then performed checkerboard resolution tests assessing resolving power these datasets. In order to overcome limited resolutions separate inversions differences in their results, we a quadruple joint inversion all data determine source model most suitable explaining model, maximum...
Abstract We propose a tsunami forecasting method based on data assimilation technique designed for dense tsunameter networks. Rather than using seismic source parameters or initial sea surface height as the condition of forecasting, it estimates current wavefield (tsunami and velocity) in real time by repeatedly assimilating into numerical simulation. Numerical experiments were performed simple 1‐D station array 2‐D layout new S‐net network around Japan Trench. Treating synthetic calculated...
Detection of shallow slow earthquakes offers insight into the near-trench part subduction interface, an important region in development great earthquake ruptures and tsunami generation. Ocean-bottom monitoring offshore seismicity off southern Kyushu, Japan, recorded a complete episode low-frequency tremor, lasting for 1 month, that was associated with very-low-frequency (VLFE) activity plate interface. The tremor exhibited two migration modes reminiscent deep down-dip seismogenic zone some...
Abstract The Sanriku ocean‐bottom seismometer system uses an optical fiber cable to guarantee real‐time observations at the seafloor. A dark connected a Distributed Acoustic Sensing (DAS) interrogator converted in array of 19,000 seismic sensors. We use these measurements constrain velocity structure under section cable. Our analysis relies on 24 hr ambient field recordings. obtain high‐resolution 2‐D shear‐wave profile by inverting multimode dispersion curves extracted from frequency‐wave...
Abstract Seismic waves from earthquakes recorded on the seafloor are composed of complex multiple arrivals. Here, distributed acoustic sensing (DAS) observations along a cable located offshore Sanriku Coast, Japan, show that local earthquake wavefield is particularly rich in Scholte waves. We introduce processing pipeline to extract these surface DAS records. then invert hundreds dispersion curves section form shallow high‐resolution shear‐wave velocity model. Moreover, we focus possible...
Recently, the distributed acoustic sensing (DAS) measurement, which utilizes an optical fiber itself as a sensor, becomes popular for various fields and is being applied to seismic observations. The shortest spatial sampling of DAS observations reaches few meters, total measurement distance greater than 50 km. A high temporal rate achieved. Due these characteristics, allows dense observation linear array. Applying seafloor cable advantageous because quantity data can be significantly...
Abstract Distributed Acoustic Sensing (DAS) is a promising technique to improve the rapid detection and characterization of earthquakes. Previous DAS studies mainly focus on phase information but less amplitude information. In this study, we compile earthquake data from two arrays in California, USA, one submarine array Sanriku, Japan. We develop data‐driven method obtain first scaling relation between magnitude. Our results reveal that amplitudes recorded by different regions follow similar...
Tsunami heights greater than 4 m were observed at several coastal tide-gauge stations during the tsunami generated by 2011 off Pacific coast of Tohoku Earthquake (Mw 9.0), causing thousands casualties and damaging infrastructure along Japan. We retrospectively applied an algorithm near-field forecasting to data that recorded various offshore 5–10 min before reached nearest its source. inverted waveform estimate distribution initial sea-surface height, then waveforms synthesized from...
After the 2011 Mw 9.1 Tohoku earthquake, numerous intraplate earthquakes occurred beneath outer slope of Japan Trench. Based on ocean bottom seismograph observations, these in oceanic crust and uppermost mantle Pacific plate at depths shallower than about 40 km had normal‐faulting focal mechanisms all depths. Before trench only 20 km, whereas those around reverse‐faulting mechanisms. These observations suggest that stress regime was changed by earthquake. The tensional stresses now extend to...
ABSTRACT Objectives We compared the effects of robot‐assisted radical cystectomy (RARC) and open (ORC) on incidence peritoneal carcinomatosis prognosis in patients with muscle‐invasive bladder cancer (MIBC) real‐world practice. Methods This retrospective study included 429 who underwent cystectomy, including RARC ( n = 151) ORC 278), at Hirosaki University Hospital Ageo Central General from 2011 to 2024. The was between groups. Potential risk factors for were identified using multivariable...
The bulk composition of the continental crust throughout geological history is thought by most previous workers to be andesitic. This assumption an andesitic led early hypothesis Taylor (1967 ) that was created arc magmatism. for origin challenged several authors because: (i) mean rate addition obtained Reymer and Schubert (1984 too small account some certain phases rapid crustal growth; (ii) ocean island arcs, main contributor Archean Proterozoic crust, basaltic rather than ( Arculus 1981 ;...
The results of a controlled source seismic reflection–refraction experiment carried out in 1992 reveal the following characteristics northern Izu–Bonin (Ogasawara) oceanic island arc–trench system. (1) crust rapidly thickens from Shikoku back‐arc basin to arc, is thickest beneath active rifts, and then gradually thins forearc. thickness arc rift zone are ∼ 20 km 8 km, respectively. (2) Moho vanishes Velocities decrease eastwards inner trench wall. (3) velocity lower 7.1–7.3 km/s. This higher...
The Nankai Trough, southwestern Japan, is recognized as a vigorous seismogenic zone with well‐studied historic earthquakes. This paper presents results of wide‐angle ocean bottom seismographs (OBS) study at the western Trough zone. OBS data used were acquired on profile (250 km long) across presumed coseismic slip 1946 Nankaido earthquake ( Ms = 8.2). main purpose seismic to obtain an entire crustal cross section for earthquake. model characterized by gentle sloping subducting oceanic crust...