The Takanodai Landslide, Kumamoto, Japan: Insights from Post-Earthquake field Observations, Laboratory Tests & Numerical Analyses

The 2016 Kumamoto Earthquakes, Japan, caused a number of geo-disasters in the Aso Volcanic Caldera, including a large-scale flow-type slope failure known as the Takanodai landslide. Between April and October 2016, the Authors conducted a series of post-earthquake geotechnical damage surveys and field investigations in the affected areas, and retrieved samples of volcanic soils to be characterized in the laboratory. In this poster, first, the Takanodai landslide is described. Then, results of monotonic and cyclic undrained torsional simple shear tests carried out on reconstituted specimens of Aso pumice are shown. Moreover, to provide insights into the failure mechanism of the Takanodai landslide, results of dynamic soil response and seismic slope stability analyses are presented. The numerical investigation confirmed that the pumice soil deposit was responsible for the landslide triggering. Besides, the combination of pore pressure build-up and large inertial forces were the key factors for the flow-type Takanodai slope failure