Slope-Failure Area Rate Caused by the Kita-Tango Earthquake

Abstract

The 1927 Kita-Tango Earthquake triggered thousands number of slope failures in the Tango Peninsula, Kyoto Prefecture. The area and number of slope failures caused by the earthquake had been investigated and reported by the Kyoto Prefectural Government in 1930. The rate of slope-failure area at each of 59 municipalities in the Kita-Tango Region was obtained based on the report. Analyses were made on the relations between the rate of slope-failure area, geological and morphological features susceptible to slope failures during seismic shaking. Results derived from these analyses can be summarized as follows.
There is a strong relationship between the rate of slope-failure aea and the distance from the earthquake faults. It is apparent that the average rate of slope-failure area is less than 1.0% when the distance from the earthquake faults ex-ceeds 10km, and almost 0% when the distance from the earthquake fault reaches about 15 km. Although the rate of slope-failure area decreases as the distance from the epicenter increases, the reationship is weeker than those of the disatnce from the earthquake faults. There are no apparent relationships between the rate of slope-failure aea, the morphological features and the relief energy. There is an apparent relationship between the rate of destroyed houses and the distance from the earthquake faults as like as the rate of slope-failure area. These results suggest that the distance from the earthquake faluts is available for prediction of the rate of slope-failure area.