Seismic activity in the area from Miyakejima to Niijima-Kozushima

*At present, the seismic activity occurring in the sea 10 km east of Kozushima continues to rise and fall, and includes events with normal fault type mechanisms. The results of GPS observation of the area show crustal movement in the area from Mikurashima, Niijima-Kozushima, and the Izu Oshima to the southern tip of the Boso peninsula. The seismic activity and crustal movement in this area are believed to be occurring in association with subterranean dike-formation magma activity in the sea to the east of Kozushima.

*The seismic activity seen previously in the area from the west of Toshima to Kozushima, which was triggered by the seismic activity and crustal movement (above), also continues.

*Activity of the sort described above?seismic activity and crustal movement in the area from Miyakejima to Niijima-Kozushima, has no recorded precedent. It is impossible to rule out the chance of more M6.0 or higher events occurring (possibly with seismic intensities on the order of 6 lower), and it will be necessary to closely monitor seismic activity in the area for the next one or two weeks.Furthermore, in the event an earthquake on the order of M5 should occur in the vicinity of Toshima, Niijima, Shikinejima, Kozushima or Miyakejima, there is the possibility that it will occasion strong vibrations (around seismic intensity 5 lower)

• Seismic activity in the sea near Niijima, Kozushima and Miyakejima(entire period)
• Seismic activity in the sea near Niijima, Kozushima and Miyakejima(Since July 15th)
• Seismic activity in the sea near Niijima, Kozushima and Miyakejima(From Toshima to Kozushima)
• Major centroid movement solutions (CMS) (for the July 20th event)
• Mechanism solutions for Niijima/Kozushima/Miyakejima
• Vector map (horizontal)
• Vector map (horizontal)
• Vector map (horizontal)
• Baseline map
• Base-line-length variation graph(1)
• Base-line-length variation graph(2)
• Base-line-length variation graph(3)
• Base-line-length variation graph(4)
• Base-line-length variation graph(5)
• Base-line-length variation graph(6)
• Base-line-length variation graph(7)
• Base-line-length variation graph(8)
• Comparison of model based on conjectural fault movements and intrusions and actual GPS observations

Corrigenda

The explanatory supplement to the Seismic Activity in June, 2000 report issued on July 12th by the Department for the Promotion of Earthquake Study and Research, Earthquake Study Committee contained an error, which should be corrected as follows:

Error: In the period from 1997 to 1999, the average annual incidence of M6.0 or greater earthquakes was eleven (or eight if events in the area of Taiwan are excluded), but there have already been eleven such events as of the end of June this year.

Correction: In the period from 1997 to 1999, the average annual incidence of M6.0 or greater earthquakes was eleven (or eight if events in the area of Taiwan are excluded), but there have already been nine such events as of the end of June this year.