TERRAPUB Earth, Planets and Space

Earth Planets Space, Vol. 58 (No. 7), pp. 911-915, 2006


Seafloor displacement at Kumano-nada caused by the 2004 off Kii Peninsula earthquakes, detected through repeated GPS/Acoustic surveys

Motoyuki Kido1, Hiromi Fujimoto1, Satoshi Miura1, Yukihito Osada1, Kentaro Tsuka2, and Takao Tabei2

1RCPEV, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
2Natural Env. Sci., Kochi University, Akebono-cho, Kochi 780-8520, Japan

(Received January 24, 2006; Revised March 13, 2006; Accepted March 15, 2006; Online published July 26, 2006)

Abstract: In 2004, we started monitoring crustal deformation at Kumano-nada in the Nankai trough using the GPS/Acoustic technique. We observed a large southward seafloor displacement of ∼30 cm associated with the off Kii Peninsula earthquake, which occurred in September 2004, between our two survey campaigns in August and November 2004. The observed seafloor displacement is larger than that predicted from a slip model derived solely from GPS measurements on land. This may indicate the earthquake fault is slightly shallower and extends move to the NW than previously estimated.
Key words: GPS/Acoustic measurement, seafloor displacement, Kumano-nada, 2004 off Kii Peninsula earthquake.

Corresponding author E-mail: kido@aob.geophys.tohoku.ac.jp

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