A5084209066- Seismic Waves and Analysis
- High-pressure geophysics and materials
- earthquake and tectonic studies
- Seismic Imaging and Inversion Techniques
- Geophysics and Sensor Technology
- Geological and Geochemical Analysis
- Geological and Geophysical Studies
- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- Earthquake Detection and Analysis
- Seismology and Earthquake Studies
- Advanced Fiber Optic Sensors
- Ultrasonics and Acoustic Wave Propagation
- Chalcogenide Semiconductor Thin Films
- Underwater Acoustics Research
- Advanced Thermoelectric Materials and Devices
- Geological Studies and Exploration
- Drilling and Well Engineering
- Geochemistry and Geologic Mapping
- Advanced Electrical Measurement Techniques
- Quantum Dots Synthesis And Properties
- Adhesion, Friction, and Surface Interactions
- Geophysical and Geoelectrical Methods
- Ionosphere and magnetosphere dynamics
- Gas Sensing Nanomaterials and Sensors
Hokkaido University
2011-2023
Osaka University
2022
Graduate School USA
2017-2018
Planetary Science Institute
2014
Lamont-Doherty Earth Observatory
2010
Columbia University
2010
Australian National University
2002-2004
Hiroshima University
1999
The mantle component of the Australian Seismological Reference Model (AuSREM) has been constructed from Australian-specific sources, primarily exploiting wealth seismic sources at regional distances around Australia recorded portable and permanent stations on continent. AuSREM is designed to bring together existing information Australia, both body wave surface studies provide a synthesis in form 3-D model that can basis for future refinement. grid based with 0.5° sampling latitude longitude,...
An approximate description of the zone influence around propagation path for a surface wave is provided by investigating Fresnel zones frequency range interest. The about paths, over which waves are coherent in phase, identified as approximately one-third width first zone. A technique called Fresnel-area ray tracing (FRT) has been used to estimate this region each frequency. FRT developed combining two standard methods, i.e. kinematic (KRT) and dynamic (DRT). To obtain exact area laterally...
A three‐stage inversion technique for surface wave tomography is applied to the Australian region. The procedure consists of three independent processes. In first stage, path‐specific one‐dimensional (1‐D) shear velocity profiles are derived from multimode waveform provide dispersion information. information all paths then combined produce phase speed maps as a function frequency. version these linearized based on assumption propagation along great circle paths. Subsequently, 2‐D updated by...
A series of steps in the lithospheric thickness eastern Australia are revealed by latest seismic surface wave tomographic model and calculations horizontal gradient shear speed. The new images incorporate data from recent Tasmal experiment, improving resolution continental Australia. Through comparisons with geology geochemical studies, it is possible to infer that related boundaries between blocks different age. westernmost boundary marks edge Archaean Early‐Proterozoic core continent....
A new technique for multimode dispersion measurement has been developed by employing fully non-linear waveform inversion a path-specific 1-D profile using neighbourhood algorithm (NA). One-dimensional models derived from are quite sensitive to the model parametrization and reference used start inversion. With different approaches of shear wave speed profile, we can find with significant differences in velocity variation depth, which provide similar levels fit observed waveforms. Although...
A 3-D upper-mantle structure beneath Turkey is investigated using phase speeds of fundamental-mode Rayleigh waves employing a conventional two-station method with high-density seismic networks in Turkey. We analyse 289 events moment magnitude 5.5 and greater, focal depth shallower than 100 km between 2006 2008. Waveform data are derived from 164 three-component broad-band stations operated by two national networks. At first, Rayleigh-wave speed maps obtained the inversion about 1000–3000...
The explosive eruption occurred at Hunga Tonga-Hunga Ha'apai on January 15, 2022, generating atmospheric waves, meteotsunamis, tsunamis, and seismic waves recorded worldwide. Energetic signals of surface indicate multiple events, but the detailed episodes are hard to unravel from dispersive long-period waves. In this study, we performed back-projection (BP) analysis using teleseismic P-waves clarify sequence eruptions. BP results successfully detected locations timing explosions even though...
Lateral structural variations in the upper mantle generate azimuthal dependence receiver functions (RFs) based on incoming directions of body waves. Although these RFs have not been considered earlier studies RF inversions, they provide a means to image localized changes interfaces. In this study, we incorporate azimuth-dependent into joint Bayesian inversion with multimode surface waves, applying approach major permanent broadband stations Australia. The resulting models reveal event...
A large devastating earthquake of Mw 7.5 struck the Noto Peninsula, Japan, on January 1st, 2024. Persistent seismic swarms have continued around hypocenter since 2020, likely driven by crustal fluids migrating upward from lower crust. In this study, we investigated frequency-dependent radiation process using multi-frequency teleseismic P-wave back projection. The resulting source reveals complex behavior, which can be divided into four episodes. initial episode lasts 15–20 s, characterized...
Abstract A new 3‐D S wave speed model for the Australian region derived from multimode surface waves allows us to examine nature of lithosphere‐asthenosphere transition (LAT) and its relation radial anisotropy. In eastern Phanerozoic Australia estimated depths LAT tie well with those receiver functions. However, in Archean Proterozoic lithosphere western central Australia, is generally much deeper than discontinuities recognized functions shows a smooth transition. There significant...
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...
The resolving power of polarization data compared with that phase is investigated by employing both synthetic and observed sets, using the linear relationship between velocity perturbation or anomaly. In order to investigate intrinsic differences data, a test first undertaken white noise model sufficiently uniform coverage ray paths. This shows can retrieve higher-order heterogeneities degrees up 20 almost completely, despite damping smoothing effects, whilst only those lower than 8...
A three-stage inversion scheme for surface wave tomography working with multimode phase dispersion as a function of frequency provides means combining wide range data in common framework. The average approximation is applied directly to slowness and there no need invoke perturbation arguments the interpretation path-averaged velocity models derived from waveform waves. By treating such speed profiles summaries path specific behaviour it possible not only combine results different style but...
Sensitivity kernels for fundamental mode surface waves at finite frequency 2-D phase speed and 3-D shear wave are constructed based on the Born Rytov approximations working with a potential representation waves. The use of asymptotic Green's functions scalar equations provides an efficient way to calculate or kernels. sensitivity enable us incorporate finite-frequency effects waves, as well off-great-circle propagation, in tomographic inversions phase-speed structures. We derive examples...
A fully automated method for obtaining multimode phase speed measurements from a single seismogram has been developed and applied to large data set of three-component long-period seismograms in North America, constructing high-resolution maps on continental scale. The our estimation is based non-linear waveform inversion by Yoshizawa & Kennett working with global search (the Neighbourhood Algorithm). entire process fitting the evaluation estimated have employing several empirical...
The seismicity of the Pacific coast Tohoku, Japan, has been investigated in detail and characterized into regional seismic segments. 2011 megathrust earthquake Mw 9.0 on 11 March ruptured almost all segments that area, causing devastating tsunamis. prime factor had not recognized before is double segmentation along Japan trench: apparent absence earthquakes trench-ward as opposed to Island-ward have repeated smaller earthquakes. We term this pattern activity 'along-dip (ADDS)'. Tohoku...
We present some singular characteristics of the 2011 off Pacific coast Tohoku Earthquake in comparison with other megathrust earthquakes, such as 1960 Chilean and 2004 Sumatra-Andaman earthquakes. In addition to conventional along-strike segmentation, along-dip segmentation fault area or subduction zone is an important feature for zone, indicated by difference background seismicity: virtually no seismicity shallow segments but active large events repeating deep segments. The interaction...