Go Sato

Finite Element Simulation for Seismic Ground Response in Mountainous Areas in Nepal

In this study, dynamic elasto-plastic finite element method is applied to simulate seismic ground response in mountainous districts in Nepal, which aims to reevaluate the earthquake-induced landslides occurred at the time of The 2015 Nepal Gorkha Earthquake. In the analysis, nonlinear material properties of the ground as well as 3D topography, geological conditions and input motion are taken into account appropriately. Those factors strongly influence the dynamic amplification effects relevant to slope failures. Throughout the comparisons of the results between the calculated one and observed facts in local areas, it can be concluded that the proposed numerical method has a sufficient ability to predict the phenomena and can be possibly utilized for predicting overall distribution of earthquake-induced landslide which would be helpful for developing landslide susceptibility maps in mountainous areas in Nepal.

Distribution of Landslides Induced in Iwaki City, Japan, by Two Large-scale Earthquakes in 2011

Iwaki City in eastern Japan experienced two large-scale earthquakes in 2011: the Tohoku earthquake that occurred on March 11 and an active fault-type earthquake that occurred on April 11. We developed a landslide distribution map of Iwaki City using aerial images and show that the landslides induced by the April 11 aftershock alone account for 70 % of all landslides induced by March 11 and April 11 earthquakes. In particular, we show that the distribution of landslides caused by the April 11 earthquake was determined by fault structure and lithological character. Furthermore, the landslides occurred along mountain ridges and in regions that previously had convex slope profiles.