Development of a flowchart for extracting places with high risk slope of failure in an earthquake around transmission towers

Abstract

The purpose of this work was to evaluate locations with high risk of slope failure in an earthquake around transmission towers using desk analysis. To this end, a flowchart was constructed for extracting such locations. The flowchart has two stages, for a large area and middle area. In the large-area stage, the flowchart is implemented based on geologic and topographic maps after selecting the form of slope failure. The middle-area stage is implemented based on a digital elevation model (DEM). Basic factors calculated from the DEM and its threshold values are determined by a case history of slope failure during past upper-crustal earthquakes. The flowchart was applied to slope failure caused by the Mid Niigata Prefecture Earthquake in 2004, which showed that locations identified by the flowchart as dangerous and those with actual failure coincided well.