2007 Volume 60 Issue 1 Pages 43-53
On August 16, 2005, a large earthquake (M 7.2) occurred along the plate boundary of off Miyagi Prefecture (Miyagi-Oki), northeastern Japan. In this area, large earthquakes (∼M 7.5) have occurred repeatedly at intervals of about 37 years, and it has passed more than 27 years since this event occurred. To understand the relation between this earthquake and the previous 1978 event, we estimated the coseismic slip distribution of the 2005 Miyagi-Oki earthquake by the seismic waveform inversion method. We used the same structure model used in the analysis of the 1978 event. By comparing the coseismic slip distribution of the 2005 Miyagi-Oki earthquake of this study with those of previous studies, we investigated the reliability and our result seems to be plausible. Then we compared our result with the previous 1978 Miyagi-Oki earthquake and found that the rupture area of the 2005 event overlapped with the southeastern part of the 1978 earthquake’s rupture area. This result supports the idea that there exist plural asperities which cause the sequence of Miyagi-Oki earthquake, and the 2005 event ruptured part of such asperities, while the previous 1978 event ruptured all of the prural asperities at one time.
