Crustal deformation by the Southeast-off Kii Peninsula Earthquake
Tetsuro IMAKIIRE, Shinzaburo OZAWA, Hiroshi YARAI, Takuya NISHIMURA and Hisashi SUITO
A series of large earthquakes occurred southeast of Kii Peninsula on September 5, 2004. The apparent crustal deformation caused by these earthquakes was detected by GEONET around central Japan. The focal mechanism estimated by seismogram records is reverse fault type with north-south P-axis. The crustal deformation observed by GEONET is generally consistent with the mechanism estimated by the seismological analysis. Even though the epicenters are near the Nankai trough, these earthquakes were not the plate boundary thrust type as indicated by the dip angle of the fault, which does not coincide with that of the Philippine Sea plate. Lastly it was noted that the slowslip event in the Tokai region since the fall of 2000 is slightly affected by the postseismic effect of these earthquakes.