A5022833464- earthquake and tectonic studies
- High-pressure geophysics and materials
- Seismic Waves and Analysis
- Seismic Imaging and Inversion Techniques
- Geological and Geophysical Studies
- Geological and Geochemical Analysis
- Seismology and Earthquake Studies
- Earthquake Detection and Analysis
- Methane Hydrates and Related Phenomena
- Geological Studies and Exploration
- Underwater Acoustics Research
- Hydrocarbon exploration and reservoir analysis
- Geophysics and Sensor Technology
- Geophysical and Geoelectrical Methods
- Geology and Paleoclimatology Research
- Geophysics and Gravity Measurements
- Tropical and Extratropical Cyclones Research
- Oceanographic and Atmospheric Processes
- Ocean Waves and Remote Sensing
- Geomagnetism and Paleomagnetism Studies
- Earthquake and Tsunami Effects
- Reservoir Engineering and Simulation Methods
- Coastal and Marine Dynamics
- Orthodontics and Dentofacial Orthopedics
- Geochemistry and Geologic Mapping
Japan Agency for Marine-Earth Science and Technology
2016-2025
Earth University
2015-2018
EarthSky
2015-2018
Utsunomiya University
2002-2014
Tokyo Metropolitan Ohtsuka Hospital
2007-2008
Tokyo Dental College
2007
University of Occupational and Environmental Health Japan
2002
Tohoku University
1996-2002
The processes that create continental crust in an intraoceanic arc setting are a matter of debate. To address this issue, we conducted active source wide‐angle seismic study to examine along‐arc structural variations the Izu arc. data used were acquired over 550‐km‐long profile along volcanic front from Sagami Bay Tori‐shima. obtained model showed existence felsic intermediate composition middle with P wave velocity (Vp) 6.0–6.5 km s −1 its upper part and 6.5–6.8 lower part. thickness varied...
A giant earthquake occasionally occurs in a subduction zone owing to simultaneous rupture adjacent segments which have been previously ruptured by large earthquakes. However, it is still unknown if coincidentally occurs, or there causal factor control its generation. In this study we show cause and growth process of may occur along southwestern Japan, on the basis seismic images obtained from wide‐angle data numerical simulation incorporating structural images. The were acquired three trough...
On August 17, 1999, a destructive earthquake occurred in the western part of North Anatolian Fault Zone, Turkey. The source region has been designated as seismic gap and an M7-class supposed to occur someday future so fill this gap. So far we have undertaken various kinds observations area could obtain some valuable data before, during after mainshock. Here report preliminary results our recent studies, which include field work started late July year continued occurrence just its vicinity,...
We present the results of an onshore–offshore wide‐angle refraction and reflection experiment off Miyagi, in central Japan Trench forearc region. There are two rupture zones large interplate earthquakes here: landward zone trenchward zone. To examine influence plate boundary geometry on distributions zones, we determined reflector geometries from reflections. The subducting oceanic increases its dip about 5° to 13° around 143.2°E. This bending point corresponds eastern edge Moreover, another...
To investigate megathrust earthquake and tsunami generation in a subduction seismogenic zone, it is important to know the detailed structure around plate boundary active splay‐fault system. The Nankai Trough, southwestern Japan, among best studied zones with splay faults world. This paper presents structural image fault coseismic rupture zone of 1944 Tonankai central based on results from wide‐angle, high‐density ocean bottom seismograph (OBS) survey. Our seismic clearly shows for first time...
The subduction of active spreading centers is an unusual phenomenon along zones. In southern Chile, the Nazca-Antarctic system (Chile Rise) subducts beneath South American plate at Chile Triple Junction (CTJ), forming Patagonian slab window. onset window has been estimated based on kinematic reconstructions, but direct observations remain insufficient. To study this tectonic feature in detail, Ocean Bottom Seismometer (OBS) array was deployed south CTJ between 2019 and 2021, many earthquakes...
<title>Abstract</title> An increase in seismic activity was observed near the Izu-Torishima and Sofugan islands Izu-Ogasawara arc of Japan early October 2023. Several M6-class earthquakes occurred from 3 to 6, tsunamis were recorded on 5 associated with normal faulting earthquakes. On 8, without any significant but accompanied by distinct T-phase signals. Analyses T-phases, tsunami waveforms, bathymetry surveys suggested that 8 linked volcanic at Sofu Seamount, located west Island. However,...
We analyze seismic waveforms from deep‐focus earthquakes occurring in the subducting slab beneath Japan, recorded by broadband ocean bottom seismometers (BBOBSs) installed on northwestern Pacific Ocean seafloor. The data reveal with a low‐frequency direct P onset, followed large‐amplitude, high‐frequency, long‐duration Po and So waves. From analysis of BBOBS records numerical finite‐difference method simulation wave propagation, we elucidate generation propagation processes such guided...
Electric and magnetic data were obtained above the focal area in association with 1999 Izmit, Turkey earthquake. The acquired are extremely important for studies of electromagnetic phenomena associated earthquakes, which have attracted much attention even without clear physical understanding their characteristics. We already reported that large electric variations observed during earthquake simply due to seismic waves through mechanism dynamo effect, because they appeared neither before nor...
Abstract The Ontong Java Plateau in the western Pacific Ocean is world’s largest oceanic plateau. It was formed 122 million years ago by a massive volcanic event that significantly affected Earth’s environment. cause of magmatic remains controversial because upper mantle structure beneath plateau poorly known. Here we use passive seismic data obtained through seafloor observations, alongside existing data, to determine three-dimensional radially anisotropic shear wave velocity depths up 300...
In order to investigate the resistivity structure beneath northern and southern branches of western part North Anatolian Fault Zone (NAFZ), which has been known as a seismic gap area, we started wideband magnetotelluric (MT) measurements on 27 July 1999, along north-south profile crossing branch near Izmit Iznik. When (Kocaeli) earthquake ( M w 7.4) occurred 17 August MT fields were being measured at five sites, four happened be located surface rupture zone associated with mainshock, large...
We conducted geophysical observations on the French Polynesian seafloor in Pacific Ocean from 2009 to 2010 determine mantle structure beneath Society hotspot, which is a region of underlying volcanic activity responsible for forming Islands. The network Tomographic Investigation by ARray Experiment hotspot (TIARES, named after most common flower Tahiti) composed multi-sensor stations that include broadband ocean-bottom seismometers, electro-magnetometers, and differential pressure gauges....
Anomalously large tsunamis generated by a submarine volcanic earthquake were recorded an ocean bottom pressure gauge array.
Abstract We conducted broadband dispersion survey by deploying two arrays of ocean bottom seismometers in the northwestern Pacific Ocean at seafloor ages 130 and 140 Ma. By combining ambient noise teleseismic surface wave analyses, curves Rayleigh waves were obtained a period range 5–100 s then used to invert for one‐dimensional isotropic azimuthally anisotropic β V ( SV ) profiles beneath each array. The show ~2% difference low‐velocity zone (LVZ) depth 80–150 km spite small horizontal...
Abstract We analyzed seismic ambient noise and teleseismic waveforms of nine broadband ocean bottom seismometers deployed at a 60 Ma seafloor in the southeastward Tahiti island, South Pacific, by Tomographic Investigation ARray Experiment for Society hotspot project. first obtained one‐dimensional shear wave velocity model beneath array from average phase velocities Rayleigh waves period range 5–200 s. The shows large reduction depths between 40 80 km, where lithosphere‐asthenosphere...
Abstract No great earthquakes have been historically documented at the Izu‐Bonin Trench, where subduction is believed to occur largely by aseismic slip, although details are poorly understood. We deployed an array of ocean bottom pressure gauges here for a year from May 2015. The recorded coseismic seafloor uplift/subsidence and tsunamis generated nearby Mw6.0 thrust earthquake. In association with this event, we detected two much larger slip events rise times around 1 h. total moment these...