The 2005 M7.2 MIYAGI-OKI earthquake, NE Japan: Possible rerupturing of one of asperities that caused the previous M7.4 earthquake

A large (M7.2) interplate earthquake occurred on 16 August 2005 in the Miyagi-Oki region, where large interplate earthquakes with magnitude of ∼7.5 have occurred repeatedly at a recurrence interval of ∼37 yrs, NE Japan. We compared aftershock distribution of the 2005 Miyagi-Oki earthquake with that of the previous 1978 Miyagi-Oki earthquake (M7.4) using double-difference hypocenter locations. The aftershock area of the 2005 Miyagi-Oki earthquake is partly overlapped with the southern/ southeastern part of that of the 1978 event. Locations of aftershock clusters of the 2005 event correspond with those of the 1978 event and those of the background seismicity. Coseismic slip area of the 2005 event estimated by seismic waveform. inversion is also partly overlapped with that of the 1978 event. These observations suggest that spatial seismicity pattern on the plate boundary in subduction zone persists and the 2005 event possibly raptured a part of the source area of the 1978 event.