Earth Planets Space, Vol. 63 (No. 7), pp. 643-648, 2011
Takeshi Iinuma1, Mako Ohzono1,2, Yusaku Ohta1, and Satoshi Miura1,3
1Research Center for Prediction of Earthquakes and Volcanic Eruptions, Tohoku University, Sendai 980-8578, Japan
2Institute of Seismology and Volcanology, Hokkaido University, Sapporo 060-0810, Japan
3Earthquake Research Institute, the University of Tokyo, Tokyo 113-0032, Japan
(Received April 19, 2011; Revised June 1, 2011; Accepted June 8, 2011; Online published September 27, 2011)
We investigated the crustal deformation associated with the 2011 off the Pacific coast of Tohoku Earthquake (M 9.0) that occurred on March 11, 2011, along the plate boundary off Tohoku district, northeastern Japan, based on dense GPS observation. Coseismic displacements due to this event were applied to estimate the causal interplate slip by means of a geodetic inversion analysis. The major slip area is located around the asperities of the 1981 Miyagi-oki (M 7.2) and 2003 Fukushima-oki (M 6.8) earthquakes and the maximum slip is estimated as being up to 35 m. The estimated slip distribution suggests that the asperities of the Miyagi-oki earthquake in 1978 (M 7.4) that had not been ruptured during the Miyagi-oki earthquake in 2005 were ruptured as a part of the main shock fault of the 2011 off the Pacific coast of Tohoku Earthquake.
Key words: 2011 off the Pacific coast of Tohoku Earthquake, interplate earthquake, GPS, slip distribution, Miyagi-oki earthquake.