29 June 2000
Headquarters for Earthquake Research Promotion
Earthquake Research Committee

Seismic activity in the area of Miyakejima Island and the sea near Niijima and Kozushima Islands in June, 2000

There has been continued seismic activity in the area of Miyakejima, Niijima and Kozushima Islands since the inception of volcanic activity on Miyakejima on 26 June.

The zone of activity, which was initially in the vicinity of western Miyakejima, moved westward into the sea and continues to be active. Also, at 12:11 p.m. on 29 June, there was an M5.2 (tentative data) event in the sea near Kozushima and seismic intensity of 5 lower was recorded near the hypocenter. There has continued to be scattered seismic activity in the vicinity of Kozushima since that event.

There is the possibility that the current seismic activity will follow the pattern of past activity in the area - in 1962 there was seismic activity in the sea west of Miyakejima, including events of seismic intensity 4 to 5, which continued for one week and abated after one month. Since the results of GPS observation showed changes in the area from Miyakejima to Kozushima, the possibility is thought that the seismic activity near Kodusima was induced by a dynamic change in the crust which the volcanic activity of Miyakejima affected.