A statistical model of temporal variation of seismicity in the inner zone of southwest Japan related to the great interplate earthquakes along the Nankai Trough

Abstract

To evaluate the temporal variation of seismicity in the Inner Zone of Southwest Japan before and after the Nankai trough events, a statistical model and the value of the model parameters was estimated. Data of disastrous earthquakes was introduced to estimate them. The results show that for the northern Kinki region the seismicity has a peak before the Nankai trough events, although there is no significant change before them in the whole Inner Zone of Southwest Japan. The seismicity in the Inner Zone of Southwest Japan increases just after the Nankai trough events. The obtained intensity functions were compared with the recent JMA data from 1885 to 1995. The seismicity seems to have increased in the last 30 years. Using data from this period, we estimated the occurrence time of the next Nankai trough event. The results show that it will occur in the 2020s.