11:45 AM - 12:00 PM
[HDS09-09] Rock avalanches controlled by a thrust fault and river incision in an accretionary complex of the Shimanto Belt
Keywords:rock avalanche, thrust, river incision, accretionary complex, gravitational slope deformation, rain
As a result, we found out that the two large rock avalanches have the main sliding surfaces corresponding to the same thrust (we named the Kawarabi thrust) with the clayey brittle fracture zone with the maximum width of 6 m. Two landslides slid under the condition of wedge failure consisting of the Kawarabi thrust and some high-angle faults. It is estimated that the gravitational deformations started at the timing when the depth of the Kawarabi thrust under the slope toe reached the threshold value. The Kawarabi thrust has the clayey crushed materials to the surrounding rock mass, and form the discontinuity of ground water, and prevent the ground water flows, and builds up the pore water pressure in the heavy rain.