歴史地震の研究(5) : 宝永4年10月4日(1707年10月28日)の地震及び津波災害について

Abstract

The earthquake and tsunami damages caused by the Hoei earthquake of 1707 are investigated from collected old documents for understanding the damage locality and the occurrence characteristics of an earthquake in off Tokaido and Nankaido districts. The distribution of seismic intensity and tsunami inundation heights are also studied. Tokaido and Nankaido districts along the Pacific coasts were hit by the tsunami of this earthquake. Most severe inundation heights are estimated at about twenty six meters at Kure in Kochi Prefecture, Shikoku, Japan. This earthquake is considered to be formed of two earthquakes, of which epicenters are assumed as longitude 137.8°E, latitude 34.1°N in Enshunada (Tokaido) and longitude 134.8°E, latitude 33.2°N off west of Kii Peninsula (Nankaido), respectively. Time interval of these two Tokai and Nankai earthquakes is estimated at about 1-2 hours. It is estimated that more than thirty thousand peoples were drowned and more than thirty thousand houses were wrecked or washed away in total by the Hoei earthquake and tsunami. The magnitude of the Hoei earthquake is estimated at 8.3-8.4 for the Tokai and 8.4 for the Nankai earthquake, respectively.