Earth Planets Space, Vol. 63 (No. 7), pp. 627-630, 2011
Takeo Ito, Kazuhiro Ozawa, Tsuyoshi Watanabe, and Takeshi Sagiya
Research Center for Seismology, Volcanology and Disaster Mitigation, Graduate School of Environmental Studies, Nagoya University
(Received April 12, 2011; Revised June 14, 2011; Accepted June 15, 2011; Online published September 27, 2011)
We analyze geodetic observation data associated with the 2011 Tohoku Earthquake to estimate coseismic and early postseismic fault slip distribution on the Pacific plate interface. The maximum slip and the moment magnitude of the main shock are about 60 m and Mw 9.0, respectively. The location of the main slip patch is complementary to the source region of large earthquakes at least for those which have occurred during the last 100 years, and the maximum slip was corresponded to a release of stress accumulation for about 700 years. Source regions of the 1936, 1938, and 1978 earthquakes are considered to have been re-ruptured in the 2011 main shock, where the slip amount was significantly smaller than the main patch.
Key words: Large coseismic slip distribution, geodetic data, geodetic inversion.