HR: 1330h
AN: S52B-0143    [PDF]
TI: Source Process of The 1923 Kanto Earthquake From Geodetic, Teleseismic And Strong Motion Data
AU: * Kobayashi, R
EM: reiji@eri.u-tokyo.ac.jp
AF: Earthquake Research Institute, University of Tokyo., 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113-0032 Japan
AU: Koketsu, K
EM: koketsu@eri.u-tokyo.ac.jp
AF: Earthquake Research Institute, University of Tokyo., 1-1-1, Yayoi, Bunkyo-ku, Tokyo, 113-0032 Japan
AB: The available geodetic (Matsu'ura et al, 1980) and teleseismic data (Kanamori, 1971) were studies by Wald and Somerville (1995) for the source process of the 1923 Kanto earthquake. Recently, Takemura et al. (2003) and Kikuchi et al. (2003) compiled historical strong motion seismograms. These dataset are combined and the inversion method of Yoshida et al. (1996) is applied for a detailed image of the source process. We first invert the geodetic data alone, since they are plentiful, high quality and self-consistent. The parameters of the fault model are determined based on the model of Wald and Somerville (1995). The fault is divided into 10x7 subfaults. The slip directions of the subfaults can vary by using a linear combination of 90- and 180- degree slips. Their magnitudes are determined by the inversion. The inversion result shows that there are two asperities. The larger one with the maximum slip of 11 m is located around the Uraga Channel between the Miura and Boso Peninsulas, and the second one with a slip of 9 m appears around the base of the Izu Peninsula, where the hypocenter is located. The slip direction changes from a right-lateral strike slip around the hypocenter to a thrust slip around the Uraga Channel. These features of the recovered slip distribution are consistent with the result of Wald and Somerville (1995), but the total seismic moment is slightly larger than their one. The calculated geodetic data show good agreement with the observed ones. We then invert the geodetic and teleseismic data jointly, and will finally carry out a joint analysis of all the geodetic, teleseismic and strong motion data. The geodetic data are insensitive to the deep slips. The seismic data, in particular near-field data, can improve the slip distribution in the deeper portion. The seismic data can also determine the temporal variation of slip. Two arrivals of S-wave are recognized in the horizontal component at several stations. They may be correspond to the two asperities inferred from geodetic data, and provide a constraint on the rupture process.
DE: 1242 Seismic deformations (7205)
DE: 7200 SEISMOLOGY
DE: 7203 Body wave propagation
DE: 7209 Earthquake dynamics and mechanics
DE: 7212 Earthquake ground motions and engineering
SC: Seismology [S]
MN: 2003 Fall Meeting