Examination of Northeast Edge of the 1952 Tokachi-oki Earthquake Tsunami Source Based on Eyewitness Accounts Stated in Previously Published Reports

Abstract

We compiled eyewitness accounts of the first tsunami arrivals of the 1952 Tokachi-oki earthquake (M_t8.2), obtained east of Kushiro, Hokkaido, from previously published reports in order to estimate the northeast edge of the tsunami source. Large scatter in reported tsunami travel times obstructed to determine the edge uniquely. A careful evaluation of the reports discriminated reliable tsunami travel times from not-reliable ones. In addition, all the reported tsunami travel times were judged as the first wave peaks rather than the first wave onsets. The reliable travel times indicate that the northeast edge of the 1952 tsunami source extended to at least off Akkeshi Bay, and probably farther east.