open access

https://hdl.handle.net/2115/57964

Seismic Activity off Tokachi Region, Southeastern Hokkaido, Japan : The Features for 51 Years since the 1952 Tokachi-Oki Earthquake

日本語

low seismic activity

2004-03-25

日本地震学会

地震. 2輯

56(4)

393-403

We investigate seismic activity off Tokachi region, southeastern Hokkaido, Japan, where the Pacific plate is subducting beneath the overriding plate, by analyzing hypocenter catalogues produced at Hokkaido University and Japan Meteorological Agency. The time-space distribution of the earthquakes clearly shows a decline in seismic activity in the focal region of the Tokachi-oki earthquake of 4 March 1952 (M8.2) from the early 1990's to the present. Remarkable low seismic activity on the focal region of the 1952 earthquake indicates strong plate coupling. It also implies full stress accumulation generated through relative plate motion without energy release either by seismic or aseismic events after the 1952 event. A simple integration of relative displacement between the two plates after the latest event is approximated at 4.2m. This value equals the mean slip of 4m resulting from the 1952 earthquake. These facts point to a possible occurrence of the next great earthquake with M≥8 in the near future.

学術雑誌論文

Version of Record

0037-1114

1883-9029