HR: 10:50h
AN: S12A-03    [Abstracts]
TI: Slip Distributions Of The 2004 Off Kii-peninsula Earthquakes (Mw 7.3, 7.5) Estimated By Joint Inversion Using Tsunami Waveforms And Crustal Deformation Data
AU: * Kusunose, T
EM: kusunose@eos.hokudai.ac.jp
AF: Institute of Seismology and Volcanology,Hokkaido University, Kita-10,Nishi-8,Kita-ku, Sapporo, 060-0810 Japan
AU: Tanioka, Y
EM: tanioka@eos.hokudai.ac.jp
AF: Institute of Seismology and Volcanology,Hokkaido University, Kita-10,Nishi-8,Kita-ku, Sapporo, 060-0810 Japan
AU: Satake, K
EM: kenji.satake@aist.go.jp
AF: National Institude of Advanced Industrial Science and Technology, Site C7 1-1-1 Higashi, Tsukuba, 305-8567 Japan
AU: Baba, T
EM: babat@jamstec.go.jp
AF: Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima-cho, Yokosuka, 237-0061 Japan
AU: Hirata, K
EM: hiratak@jamstec.go.jp
AF: Japan Agency for Marine-Earth Science and Technology, 2-15 Natsushima-cho, Yokosuka, 237-0061 Japan
AU: Iwasaki, S
EM: cuh@bosai.go.jp
AF: National Reserch Institute for Earth Science and Disaster Prevention, 3-1 Tennoudai, Tsukuba, 305-0006 Japan
AU: Kato, T
EM: teru@eri.u-tokyo.ac.jp
AF: Earthquake Reserch Institute,University of Tokyo, 1-1-1,Yayoi, Bunkyo-ku, Tokyo, 113-0032 Japan
AU: Koshimura, S
EM: koshimura@tsunami2.civil.tohoku.ac.jp
AF: Disaster Control Reserch Center,Graduate School of Engineering,Tohoku University, Aoba 06, Sendai, 980-8579 Japan
AU: Hasegawa, Y
EM: yhasegaw@mri-jma.go.jp
AF: Seismology and Volcanology Reserch Department,Meteorological Reserch Institute, 1-1 Nagamine, Tsukuba, 305-0052 Japan
AU: Imakiire, T
EM: imq@gsi.go.jp
AF: Geographical Survey Institute, 1 Kitagou, Tsukuba, 305-0811 Japan
AB: On 5 September 2004, two earthquakes (Mw 7.3, 7.5) occurred at off the Kii-peninsula. Both earthquakes generated a large tsunami recorded at tide gauges along the Pacific coast of Honshu, ocean bottom pressure gauges and a GPS tsunami gauge. The crustal deformation on land had been observed by the continuous GPS observation system(GEONET) operated by Geographical Survey Institute(GSI), and the ocean bottom crustal deformation near the epicenters had been observed by the Observation System for Ocean Bottom Crustal Deformation operated by Nagoya University (http://www.seis.nagoya-u.ac.jp/~tadokoro/obcd.gaiyou.html). In this study, we estimated the slip distribution of two events by joint inversion of tsunami waveforms and horizontal crustal deformation data. We used tsunami waveforms observed at 6 tide gauge stations, 7 ocean bottom pressure gauges, a GPS tsunami gauge. We also used horizontal crustal deformation data observed at 151 GPS sites and one Observation System for Ocean Bottom Crustal Deformation. For this earthquake, two different fault models, fault model1 by Yamanaka (http://www.eri.u-tokyo.ac.jp/sanchu/Seismo_Note/2004/EIC153.html) and fault model2 by Yagi (http://iisee.kenken.go.jp/staff/yagi/eq/Japan20 040905/Japan20040905_1-j.html), are suggested using seismic waveform analysis. The fault models we used in this study are referred to these two fault models. The slip distribution of two earthquakes were estimated by using tsunami waveforms from two earthquakes and the coseismic horizontal displacement data which include the displacements of both earthquakes. The observed tsunami waveforms were equally explained by the synthetic waveforms calculated from fault model1 and fault model2. However, the observed crustal deformation data are well explained by the computed data from the fault model2, but not by those from the fault model1. The slip distribution using the fault model2 estimated by joint inversion shows that the maximum slip amount of the first event is 1.3m, that of the second event is 3.2m. The seismic moments of the first and second events are 5.0x10¹⁹[Nm](Mw=7.1), 1.7x10²⁰[Nm](Mw=7.4) respectively.
DE: 4564 Tsunamis and storm surges
DE: 7215 Earthquake source observations (1240)
DE: 8170 Subduction zone processes (1031, 3060, 3613, 8413)
SC: Seismology [S]
MN: Fall Meeting 2005