Japan Geoscience Union Meeting 2015

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Symbol S (Solid Earth Sciences) » S-CG Complex & General

[S-CG57] Structure, evolution and dynamics of mobile belts

Wed. May 27, 2015 4:15 PM - 6:00 PM A06 (APA HOTEL&RESORT TOKYO BAY MAKUHARI)

Convener:*Toru Takeshita(Department of Natural History Sciences, Graduate School of Science, Hokkaido University), Hiroshi Sato(Earthquake Prediction Research Center, Earthquake Research Institute, The University of Tokyo), Koichiro Obana(Research and Development Center for Earthquake and Tsunami, Japan Agency for Marine-Earth Science and Technology), Takuya NISHIMURA(Disaster Prevention Research Institute, Kyoto University), Yukitoshi Fukahata(Disaster Prevention Research Institute, Kyoto University), Aitaro Kato(Graduate School of Environmental Studies, Nagoya University), Jun Muto(Department of Earth Sciences, Tohoku University), Katsushi Sato(Division of Earth and Planetary Sciences, Graduate School of Science, Kyoto University), Shuichi Kodaira(Institute for Research on Earth Evolution Japan Agency for Marine-Earth Science and Technology), Takeshi Sagiya(Disaster Mitigation Research Center, Nagoya University), Tatsuya Ishiyama(Earthquake Research Institute, University of Tokyo), Makoto MATSUBARA(National Research Institute for Earth Science and Disaster Prevention), Yasutaka Ikeda(Department of Earth and Planetary Science, Graduate School of Science, University of Tokyo), Chair:Bunichiro Shibazaki(International Institute of Seismology and Earthquake Engineering, Building Research Institute)

5:45 PM - 6:00 PM

[SCG57-P35] Study on heterogeneous structure beneath the Beppu-Haneyama fault zone

3-min talk in an oral session

*Megumi KAMIZONO1, Satoshi MATSUMOTO2, Manami NAKAMOTO2, Masahiro MIYAZAKI1 (1.Department of Earth and Planetary Sciences, Graduate School of Sciences, Kyushu University, 2.Institute of Seismology and Volcanology, Faculty of Sciences, Kyushu University)

Keywords:Beppu-Haneyama fault zone, heterogeneous structure, reflector

The Beppu-Haneyama fault zone is the active fault zone in Japan, running from the Beppu Bay to western part of Oita prefecture. In the Beppu area, the seismogenic layer is thin (about 10km). Since the structure beneath this layer could affect the thickness, we need to get acquaintance of subsurface structure. This study estimated the heterogeneous structure of this fault zone from distribution of the reflectors based on seismological analysis.
We analyzed the data observed at seismic stations deployed by Kyushu and Kyoto Universities, NIED and JMA. For simplicity, we assumed homogeneous velocity structure to analyze the observed data. Normal move-out (NMO) processing was applied to detect reflectors. Seismic section normal to the strike direction of the fault zone reveals that reflective zone of the depth about 25km, which could correspond to the Moho discontinuity. Since numerous reflected waves beneath the seismogenic zone were detected. The distribution of the reflectors generating these reflected phase might relate to the thickness of the zone.