HR: 0800h
AN: S31A-0205    [Abstracts]
TI: Complex fault system of recent earthquakes in Central Japan by dense seismic observations
AU: * Sakai, S
EM: coco@eri.u-tokyo.ac.jp
AF: Earthquake Research Institute, University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113- 0032, Japan
AU: Kato, A
AF: Earthquake Research Institute, University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113- 0032, Japan
AU: Kurashimo, E
AF: Earthquake Research Institute, University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113- 0032, Japan
AU: Igarashi, T
AF: Earthquake Research Institute, University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113- 0032, Japan
AU: Iidaka, T
AF: Earthquake Research Institute, University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113- 0032, Japan
AU: Hirata, N
AF: Earthquake Research Institute, University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113- 0032, Japan
AU: Iwasaki, T
AF: Earthquake Research Institute, University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113- 0032, Japan
AU: Kanazawa, T
AF: Earthquake Research Institute, University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113- 0032, Japan
AU: observation of 2007 Noto Earthquake, G
AU: observation of 2007 Niigata Earthquake, G
AB: Some earthquakes of the transverse fault occurred in Central Japan, recently. A temporal dense seismic array was deployed the day after the main shocks to determine the major source faults responsible for the main shock and large aftershocks. Using the high-resolution seismic data, it was clarified that they were not one fault plane but two or more fault planes. For example, in a case of the 2004 Niigata prefecture Chuetsu Earthquake two parallel faults dipping steeply to the west located 5 km apart, and another dipping eastward and oriented perpendicular to the west-dipping faults. The strong heterogeneity of the crust is related to the complex geological and tectonic evolution of the area. The complexity of the fault system was clarified by a dense seismic observation. We will show the following cases: the 2004 Niigata Prefecture Chuetsu Earthquake, the 2004 off Kii Peninsula Earthquake, the 2007 Noto Hanto Earthquake and the 2007 Niigata Prefecture Chuetsu Offshore Earthquake. And we have started a new project, the Special Project for Earthquake Disaster Mitigation in the Metropolitan Tokyo area. The core item of this project is a dense seismic array observation in metropolitan area, which is called the MeSO-net (Metropolitan Seismic Observation network). It is a purpose of this observation to clarify the more detailed geometry and physical properties of the Philippine Sea Plate beneath the Tokyo area.
DE: 7205 Continental crust (1219)
DE: 7215 Earthquake source observations (1240)
DE: 7294 Seismic instruments and networks (0935, 3025)
SC: Seismology [S]
MN: 2007 Fall Meeting