2024-03-29T13:33:43Zhttps://eprints.lib.hokudai.ac.jp/dspace-oai/requestoai:eprints.lib.hokudai.ac.jp:2115/579642022-11-17T02:08:08Zhdl_2115_20039hdl_2115_116十勝沖の地震活動 : 1952年十勝沖地震以降51年間の地震活動の特徴Seismic Activity off Tokachi Region, Southeastern Hokkaido, Japan : The Features for 51 Years since the 1952 Tokachi-Oki Earthquake高橋, 浩晃笠原, 稔Tokachi-okiseismicityseismic quiescenelow seismic activity450We 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.日本地震学会Journal Articleapplication/pdfhttp://hdl.handle.net/2115/57964https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/57964/1/Zisin_56_393-.pdf0037-11141883-9029地震. 2輯5643934032004-03-25jpninfo:doi/10.4294/zisin1948.56.4_393publisher