A5080145461- Geophysical and Geoelectrical Methods
- Earthquake Detection and Analysis
- Seismic Waves and Analysis
- Geophysical Methods and Applications
- Geomagnetism and Paleomagnetism Studies
- Seismology and Earthquake Studies
- Geological and Geophysical Studies
- earthquake and tectonic studies
- Geophysics and Gravity Measurements
- Geological and Geochemical Analysis
- Seismic Imaging and Inversion Techniques
- Geotechnical and Geomechanical Engineering
- Geochemistry and Geologic Mapping
- Non-Destructive Testing Techniques
- Methane Hydrates and Related Phenomena
- Ionosphere and magnetosphere dynamics
- Atmospheric and Environmental Gas Dynamics
- Geology and Paleoclimatology Research
- Earthquake and Disaster Impact Studies
- Remote Sensing and Land Use
- Electrical and Bioimpedance Tomography
- X-ray Diffraction in Crystallography
- Solar and Space Plasma Dynamics
- Atmospheric Ozone and Climate
- Inertial Sensor and Navigation
Kyoto University of Education
2020-2025
Kyoto University
2013-2022
Graduate School USA
2014-2015
Arge Vegetationsökologie und Landschaftsplanung
2015
Hokkaido University
1996-2014
National Institute of Advanced Industrial Science and Technology
2008
Abstract Broadband magnetotelluric (MT) measurements were conducted in 2010 and 2011 the vicinity of Shinmoe‐dake Volcano Kirishima volcano group, Japan, where sub‐Plinian eruptions took place 3 times during 26–27 January 2011. By combining new observations with previous MT data, it is found that an anomalous phase excess 90° commonly observed northern sector group. Because not explained by 1‐D or 2‐D structure isotropic resistivity media, 3‐D inversions performed. applying small errors to...
A long period Pc5 pulsation was observed at Phimai in Thailand, shortly after the origin time of Sumatra earthquake on December 26, 2004. The localized nature and oscillations suggest that magnetic generated by dynamo action lower ionosphere, set up an atmospheric pressure pulse which propagated vertically as acoustic wave when ocean floor suddenly moved vertically. It is speculated a Pc3 type Tong Hai China, 10 degrees north latitude, result field line resonance with magneto‐sonic from...
Magnetic inversion is one of the popular methods to obtain information about subsurface structure. However, many conventional have a serious problem, that is, linear equations be solved become ill-posed, under-determined, and thus, uniqueness solution not guaranteed. As result, several different models fit observed magnetic data with same accuracy. To reduce non-uniqueness model, studies introduced regularization method based on quadratic norm. these impose certain level smoothness, as...
We collected audio-magnetotelluric (AMT) data across Usu volcano, Hokkaido, Japan, which erupted in 1977 and is still active. had a profile of 17 sites perpendicular to the regional tectonic strike, crossed cryptodome, Usu-Shinzan. Tensor-decomposed were interpreted by two-dimensional inversion. Outside crater rim, resistivity structure simple. The resistive somma lava underlain conductive substratum, implying altered Tertiary or Quaternary rocks. In crater, there are two bodies bisected...
Abstract Iwo‐yama volcano, part of the Kirishima Volcanic Complex, has recently shown signs unrest. We conducted a hypocenter relocation shallow earthquakes and broadband magnetotelluric measurements around Iwo‐yama. Three‐dimensional inversion data revealed an electrically conductive layer that is interpreted as hydrothermally altered clay‐dominated unit. Shallow occur beneath this layer, suggesting it controls location seismicity. The base corresponds to depth pressure source identified by...
SUMMARY Magnetotelluric (MT) observations have revealed subvertical electrical conductors that extend from shallow depths into the mid-crust at various geothermal zones, active volcanoes and faults worldwide. These deeply rooted typically been interpreted to represent entire zones of dedicated fluid transport through crust. We estimate high-resolution 3-D crustal resistivity structure below Kuju Volcanoes, Japan, using dense 153 broad-band MT measurement sites 40 telluric sites. The...
<title>Abstract</title> Magnetic and gravity inversion has long attracted attention research. A recent topic in such studies is the magnetic joint with constraint that derived magnetization density models are similar correlated. The purpose of this approach to reduce non-uniqueness individual models, which an inherent problem potential-field data inversion, by using constraints multiple data. Another point interest introduction sparse regularization inversion. If conventional smoothness...
Abstract At Naka‐dake cone, Aso caldera, Japan, volcanic activity is raised cyclically, an example of which was a phreatomagmatic eruption in September 2015. Using three‐dimensional model electrical resistivity, we identify magma pathway from series northward dipping conductive anomalies the upper crust beneath caldera. Our resistivity created magnetotelluric measurements conducted November–December 2015; thus, it provides latest information about reservoir geometry The center shifts north...
Abstract We investigated the magmatic–hydrothermal system of Aso Volcano, Japan, using broadband magnetotelluric (MT) data. To establish nature shallow crust, a previous resistivity model based on data from 100 measurement sites in and around volcano was revised 9 additional near Naka-dake crater, which is located central part volcano. The components MT impedance tipper vector were used to obtain structure by three-dimensional inversion. shows subvertical low-resistivity (< 1 Ωm)...
Abstract A magma supply system is identified in the upper crust beneath Aso caldera, Japan, appearing as a conductive anomaly via three‐dimensional electrical resistivity modeling. caldera contains numerous postcaldera volcanoes, with Naka‐dake cone recently experiencing eruptions at first crater, including an explosive eruption that ejected volcanic ash 11,000 m into air October 2016. The imaged by model consists of four key components: reservoir ~17 km depth corresponds to Conrad...
Continuous and repeated geomagnetic observations have been performed at 8 stations in the eastern part of Hokkaido, NE Japan, to confirm a detailed picture secular changes. The observation delineated anomalously large changes about 1 nT/year that lasted least for 3 30 years (depending on period observations) situated remarkable anomaly region. Contributions from earth's core or ionospheric origin are ruled out as source mechanisms because local distribution anomalous stations. Heat-triggered...
The M JMA 7.3 Kumamoto earthquake that occurred at 1:25 JST on April 16, 2016, not only triggered aftershocks in the vicinity of epicenter, but also earthquakes were 50–100 km away from epicenter main shock. active seismicity can be divided into three regions: (1) faults, (2) northern region Aso volcano (50 northeast mainshock epicenter), and (3) regions around volcanoes, Yufu, Tsurumi, Garan (100 epicenter). Notably, zones between these are distinctively seismically inactive. electric...
Abstract Crustal earthquake ruptures tend to initiate near fluid-rich zones. However, it is relatively unknown whether zones can further promote or arrest these ruptures. We image the electrical resistivity structure around focal area of 2016 Kumamoto sequence by using 200 sites broadband magnetotelluric data, and discuss its quantitative relationship initiation, growth, processes. The that initiated along outer edge low-resistivity (< 30 Ωm) tended become large earthquakes, whereas those...
During the past two decades, studies of Aso volcano in Japan have improved our understanding shallow hydrothermal system that exists beneath active crater this volcano. Detailed knowledge subsurface structure volcanic edifice is essential for developing a better behavior fluids and triggering mechanism eruptions. Here, we report three-dimensional (3-D) electrical resistivity model Nakadake central cone using audio-frequency magnetotelluric (AMT) data obtained during 2004–2005. The AMT were...
The present study proposes an improved conceptual model for the hydrothermal system in Tatun Volcano Group northern Taiwan. In study, audio-magnetotellurics (AMT) surveys were conducted to reveal spatial distribution of resistivity, which is highly sensitive fluids and alteration. By combining obtained resistivity structure with other geophysical geochemical evidence, following was inferred. Beneath Chishinshan, vapor-dominant fluids, supplied from a deeper part, are maintained low...
Both chemical and isotopic compositions of concentrated volcanic plumes are highly useful in evaluating the present status active volcanoes. Monitoring their temporal changes is for forecasting eruptions as well. Recently, we developed a drone-borne automatic plume sampler, called SelPS, wherein an output signal from sulfur dioxide (SO 2 ) sensor triggered pump to collect samples when SO concentration exceeded predefined threshold. In this study, added radio transmission function which...
Analytical solutions for the piezomagnetic potentials are derived strike-slip, dip-slip and tensile-opening fault motions with arbitrary dip strike angles, so as to be applicable in various types of earthquakes. These expressed composition elementary functions which identical magnetic produced by dipoles, quadrupoles octupoles distributed on plane other planes. Therefore, geomagnetic field changes due effect superposition fields these equivalent sources. Examples calculated results...