Simulation of the Initiation and Motion of Seismically Induced Aso-Ohashi Landslide During the 2016 Kumamoto Earthquake

To verify the mechanism of Aso-Ohashi landslide which is the seismically induced slope failure triggered by 2016 Kumamoto earthquake, field investigations and numerical simulations with terrain data measured by airborne laser scanners are carried out. A finite difference method (FDM) model is set up by the true terrain data. The stability of landslide region under shear strength reduction method and earthquake acceleration wave input were discussed. The effect of foreshock which caused strength reduction indicated that the critical value of strength was c = 16 kPa and ϕ = 33.87 degree. The earthquake wave made only steeply dipping region unstable and moved, but landslide hardly occurred in gently dipping region. In order to verify that only the steeply dipping region was moved due to earthquake, a GIS (Geographic Information System)-based depth average Bingham model which estimates the movement of slide mass is presented