Details of the Abstract
| Title of paper | Three-dimensional resistivity structure of the epicenter area of the 1997 Kagoshima earthquake doublet, Japan |
| List of authors |
Author, Keita Matsunaga., Co-author, Koki Aizawa., Co-author, Koichi Asamori., Co-author, Hiroki Ogawa., Co-author, Mitsuru Utsugi., Co-author, Ryokei Yoshimura., Co-author, Ken'ichi Yamazaki., Co-author, Kazunari Uchida., Co-author, Masahiro Yamaguchi., Co-author, Tomohiro Inoue., Co-author, Yuta Okuda., Co-author, Kohei Yonemori., Co-author, Hiromichi Shigematsu., Co-author, Hiromi Sunagawa. |
| Affiliation(s) |
Department of Earth and Planetary Sciences, Graduate school of Science, Kyushu University, Institute of Seismology and Volcanology, Kyushu University, Tono Geoscience Center, Japan Atomic Energy Agency, Nittetsu Mining Co., Ltd, Aso Volcanological Laboratory, Institute for Geothermal Sciences, Graduate School of Science, Kyoto University, Disaster Prevention Research Institute, Kyoto University, Disaster Prevention Research Institute, Kyoto University, Institute of Seismology and Volcanology, Kyushu University, Institute of Seismology and Volcanology, Kyushu University, Institute of Seismology and Volcanology, Kyushu University, Department of Earth and Planetary Sciences, Graduate school of Science, Kyushu University, Department of Earth and Planetary Sciences, Graduate school of Science, Kyushu University, Department of Earth and Planetary Sciences, Graduate school of Science, Kyushu University, Department of Earth and Planetary Sciences, school of Science, Kyushu University |
| Summary |
We utilized broadband magneto-telluric (MT) data to analyze the 3-D resistivity structure surrounding the epicenter of the 1997 Kagoshima Prefecture Northwestern Earthquake doublet in Japan to assess the potential for significant earthquakes (Aizawa et al., 2022, EPS). The 1997 Kagoshima northwest earthquake doublet generated a F-shaped aftershock zone extending in both east-west and north-south directions. Previous research (Umeda et al., 2014, Tectonophysics) established a resistivity structure in this region. However, this study did not investigate the relationship between earthquake rupture and resistivity structure. We expanded upon the work by incorporating additional MT data. Our dataset combines data from Umeda et al. (2014), Kyushu University (obtained in 2016,2017, and 2022) and newly acquired data (obtained in 2024), total of 86 data points. We used an unstructured tetrahedral mesh and FEMTIC code (Usui, 2015; Usui et al., 2017, GJI) for estimating a 3D resistivity structure. Input data are four components of impedance tensor and two components of Tipper at 20 frequencies (3×10^(-4) ~ 80 Hz). In the inversion, we gave the fixed air (10^8 Ωm), the fixed ocean (0.33 Ωm) and unfixed land (100 Ωm), respectively. Our findings reveal low-resistivity zones near the eastern and western edges of the aftershock region at depths of 5-10 km. The hypocenters of the M6 earthquakes are located near the edge of the low-resistivity zones. Interestingly, we observed a distinct high-resistivity zone sandwiched between two low-resistivity zones corresponding to the distribution of a granodiorite body. |
| Session Keyword | 4.0 Tectonics and geodynamics, including magmatism |
| File upload |
4.0_three-dimensional_resisti_matsunaga_03.pdf
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