A5074159971- earthquake and tectonic studies
- High-pressure geophysics and materials
- Seismic Waves and Analysis
- Seismic Imaging and Inversion Techniques
- Geological and Geochemical Analysis
- Earthquake Detection and Analysis
- Seismology and Earthquake Studies
- Geological and Geophysical Studies
- Methane Hydrates and Related Phenomena
- Geophysics and Gravity Measurements
- Quantum Chromodynamics and Particle Interactions
- High-Energy Particle Collisions Research
- Particle physics theoretical and experimental studies
- Oceanographic and Atmospheric Processes
- Geophysics and Sensor Technology
- Underwater Acoustics Research
- Geology and Paleoclimatology Research
- Geomagnetism and Paleomagnetism Studies
- Geophysical and Geoelectrical Methods
- Hydrocarbon exploration and reservoir analysis
- Geological Studies and Exploration
- Geological formations and processes
- Tropical and Extratropical Cyclones Research
- Geological and Tectonic Studies in Latin America
- Ocean Waves and Remote Sensing
Japan Agency for Marine-Earth Science and Technology
2014-2023
Geological Survey of Japan
2015-2019
RIKEN Nishina Center
2009-2016
Kyoto University
2008-2015
The University of Tokyo
1995-2014
Tokyo University of Science
2014
International Foundation for Research in Experimental Economics
2014
RIKEN
2008
Association for the Development of Earthquake Prediction
1998-2005
Institute of Particle Physics
2005
The P wave velocity structure beneath the Western Pacific is found from International Seismological Center first arrival data. Special attention was paid to deep Wadati‐Benioff zone. We discretized whole mantle into blocks with finer in region of interest obtain velocities all blocks. This way discretization minimizes a problem tomographic studies regional scale: difficulty making corrections for effects outside interest. Our solution iterative alternate step relocation earthquakes, using...
We made a region‐by‐region examination of subducted slab images along the circum‐Pacific for some recent global mantle tomographic models, specifically two high‐resolution P velocity models and long‐wavelength S models. extracted that are most consistent among different found slabs tend to be subhorizontally deflected or flattened in upper lower transition region, depth range which corresponds roughly Bullen region (400–1000 km). The reside at depths, either above across 660‐km discontinuity...
Abstract A new P wave tomographic model of the mantle was constructed using more than 10 million travel times. The finite‐frequency effect seismic rays taken into account by calculating banana‐donut kernels at 2 Hz for all first arrival time data, and 0.1 broadband differential data. Based on this model, a systematic survey subducted slab images developed circum‐Pacific; including Kurile, Honshu, Izu‐Bonin, Mariana, Java, Tonga‐Kermadec, southern northern South America, Central arcs. This...
A tsunami earthquake is defined as a shock which generates extensive tsunamis but relatively weak seismic waves. comparative study made for the two recent earthquakes, and subduction mechanism near deep‐sea trench discussed. These earthquakes occurred at extremely shallow depths far off coasts of Kurile Islands eastern Hokkaido on October 20, 1963, June 10, 1975, respectively. Both can be regarded an aftershock preceding larger events. Their heights wave amplitudes are compared with those...
Earth's free oscillations were considered to be transient phenomena occurring after large earthquakes. An analysis of records the IDA (International Deployment Accelerometers) gravimeter network shows that Earth is freely oscillating at an observable level even in seismically inactive periods. The observed are fundamental spheroidal modes frequencies between 2 and 7 millihertz. Numerical modeling indicates these incessant excitations cannot explained by stacked effects a number small...
Abstract We present a new whole mantle P wave tomographic model GAP_P4. used two data groups; short‐period of more than 10 million picked‐up onset times and long‐period 20 thousand differential travel measured by waveform cross correlation. Finite frequency kernels were calculated at the corresponding bands for both long‐ data. With respect to an earlier GAP_P2, we find important improvements especially in transition zone uppermost lower beneath South China Sea southern Philippine owing...
The Central Andes is the middle part of Andean chain between about 13°S and 27°S, characterized by parallel running high mountain chains (the Western Eastern Cordilleras) at edges plateaus with a height 4000 m width 200 to 450 km Altiplano‐Puna). From examination geophysical geological data in this area, including earthquakes, deformation, gravity anomaly, volcanism, uplift history, plate motion, we conclude that continued subduction domination compressive stress over entire arc system main...
We, for the first time, report evidence of incessant excitation Earth's free oscillations, mainly fundamental spheroidal modes in a frequency range from 0.3 to 5 mHz, based on three year record superconducting gravimeter at Syowa Station, East Antarctica. The frequency-time spectrogram this is striped by more than 30 lines nGal level parallel time axis, mostly corresponding modes. This characterized relatively efficient gravest modes, enhancement signal intensities austral winter and...
The PHENIX experiment has measured the production of ${\ensuremath{\pi}}^{0}$s in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{{s}_{\mathit{NN}}}$ $=$ 200 GeV. new data offer a fourfold increase recorded luminosity, providing higher precision and larger reach transverse momentum, ${p}_{T}$, to 20 GeV/$c$. ratio $\ensuremath{\eta}/{\ensuremath{\pi}}^{0}$ is $0.46\ifmmode\pm\else\textpm\fi{}0.01(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.05(\mathrm{syst})$, constant with ${p}_{T}$ collision...
We conducted 1‐year continuous measurements of in situ compressional wave velocity and attenuation across a distance 12 m vault at the coast Miura Bay, Japan, using piezoelectric transducer as ultrasonic source. detected, for first time, periodic variations both attenuation, with amplitudes 0.3%, 4%, respectively, corresponding to diurnal semidiurnal lunar solar tides. These correlate well areal strain change due tidal ocean loading estimated from records about 100 away observational site....
Subcrustal earthquakes occur in a slab-like zone beneath SW Japan association with the subduction of Philippine Sea plate. They generate distinct pair P and S later phases anomalously low apparent velocities about 7 4 km s1, which cannot be explained by laterally homogeneous velocity structure. These are observed for particular source–receiver geometries: sources at depths shallower than 50–60 receivers subcrustal seismic comes contact bottom continental crust. We examined nature these using...
Earth's background free oscillations known as hum have been interpreted the Earth response to vertical pressure loads due atmospheric and/or oceanic disturbances. Such excitation mechanisms, however, can hardly excite Love waves. Here we show clear evidence of waves from 0.01 0.1 Hz, based on array analysis tiltmeters in Japanese islands. The observed kinetic energy is large that Rayleigh through whole period analysis. predominant incident azimuths are common and waves, strongest directions...
Research Article| March 01, 2010 A low-velocity zone with weak reflectivity along the Nankai subduction Jin-Oh Park; Park * 1Ocean Institute, University of Tokyo, Tokyo 164-8639, Japan2Institute for on Earth Evolution, Japan Agency Marine-Earth Science and Technology, Yokohama 236-0001, *E-mail: jopark@ori.u-tokyo.ac.jp. Search other works by this author on: GSW Google Scholar Gou Fujie; Fujie 2Institute Lalith Wijerathne; Wijerathne Takane Hori; Hori Shuichi Kodaira; Kodaira Yoshio Fukao;...
This paper uses data from the Capital Area Seismograph Network in North China (NC), currently largest regional seismograph network to investigate compressional stress orientations polarizations of faster shear waves (PFS), a parameter wave velocity anisotropy. Data are restricted earthquakes deeper than 5 km reduce influence heterogeneous uppermost few kilometres crust. The results show that direction is ENE-WSW nearly EW NC, which agrees with seismic mechanisms and drilling GPS data....