TERRAPUB Earth, Planets and Space

Earth Planets Space, Vol. 57 (No. 3), pp. 167-172, 2005


Compound fault rupture during the 2004 off the Kii Peninsula earthquake (M 7.4) inferred from highly resolved coseismic sea-surface deformation

Toshitaka Baba1, Phil. R. Cummins2, and Takane Hori1

1Institute for Research on Earth Evolution, Japan Agency for Marine-Earth Science and Technology, 3173-25 Showa-machi, Kanazawa-ku, Yokohama 236-0001, Japan
2Minerals and Geohazards Division, Geoscience Australia, GPO Box 378, Canberra, ACT 2601 Australia

(Received November 30, 2004; Revised February 24, 2005; Accepted February 25, 2005)

Abstract: For a tsunami inversion analysis, we incorporated a new technique that uses many Green's functions to improve model spatial resolution. Since this method precisely reproduces observed tsunami waveforms, we can obtain a better model of the tsunami source process. We applied the proposed method to the 2004 off the Kii Peninsula earthquake to determine what fault or faults ruptured to cause the earthquake. The estimated coseismic seasurface deformation extended to two directions, and it was consistent with the distributions of the two aftershock swarms. Hence, we concluded that the earthquake resulted from the rupture of two faults.
Key words: The 2004 off the Kii peninsula earthquake, compound rupture, cosesimic sea-surface deformation, tsunami inversion, high-resolution.

Corresponding author E-mail: babat@jamstec.go.jp

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