Historical earthquakes in and around the Hokkaido, northern Japan; Special reference to the Ainu oral traditions and historical records

Niizato, Tadafumi  ; Shigeno, Kiyoyuki*; Takashimizu, Yasuhiro*

Ainu oral traditions and historical records on earthquake events in the Ainu Cultural period were investigated, and the reliability of occurrence of the past earthquake events in Hokkaido was examined. As a result of investigation, 28 oral traditions and historical records were collected from the Ainu-related literatures. Based on the examination, we interpreted 24 traditions and records as results of past earthquakes, and the others were not related to earthquakes. It is inferred that earthquake hit Hokkaido were mainly distributed around the Pacific coastal area during the Ainu Cultural period and the previous period. Those areas are adjacent to the seismically active area at present in and around Hokkaido. On estimating of probability of future seismicity by extrapolation of the past to present seismicity, it may be presumed that future distribution of earthquake will be same as that of present-day earthquake in the same future period of Ainu Cultural period.