2011 Volume 64 Issue 3 Pages 21-27
Earthquake acceleration is the main factor of slope failure triggered by an earthquake. This study investigated the relationship between the area ratio of slope failure and slope angle as well as geological properties in a 294 km2 rectangular compartment in a seismic zone off the coast of Kurosaki in Noto Kongo-kita, which was directly above the epicenter of the 2007 Noto-Hantou Earthquake. Because sufficient research has not been conducted to evaluate the area ratio of slope failure using the individual factors of soil strength, earthquake acceleration, and slope angle, we propose employing the slope unstability index (Skf), which is comprised of a slope angle factor, geological properties (cohesion and failure weight), and earthquake acceleration. GIS analysis revealed that geology determines the relation between slope angle and area ratio of slope failure (Sa) ; specifically, the soil strength of the slope is an important factor for slope failures triggered by an earthquake. Hence, the area ratio of slope failure is strongly governed by the slope unstability index (Skf).