2024 Volume 133 Issue 1 Pages 1-21
The Ansei-Tokai Earthquake occurred at around 10:00 A.M. on December 23, 1854. The seismic intensity of the earthquake tended to be greater where Shizuoka and Aichi prefectures face the Pacific Ocean. However, it is pointed out that the Kofu Basin, which is located inland, was also hit by strong motions equivalent to seismic intensity 7. A detailed seismic intensity distribution map of the Kofu Basin has been revised several times. However, the historical records are biased toward the western part of the Kofu Basin; as a result, seismic intensity tends to be higher in the western part of the basin. New historical records clarify damage to houses at each village in the eastern part of the Kofu Basin. Seismic intensity is estimated from the damage rate of houses identified. As a result, two new IDPs (intensity data point) with seismic intensity 7 and six new IDPs with seismic intensity 6-7 are added. It is observed that not only the western part of the Kofu basin but also the eastern part of the basin was hit by strong seismic motions. Regional bias of seismic intensity within the basin is updated, which allows a reexamination of the distribution of seismic intensity.
