2:15 PM - 2:30 PM
[HDS09-11] The role of thrust faults with incohesive clayey fault materials to generate deep-seated gravitational slope deformations and catastrophic landslides in the Shimanto accretionary complex
Keywords:deep-seated catastrophic landslide, gravitational slope deformation, incohesive clayey fault material, accretionary complex
As a result, we obtained the following results and conclusions.
1. Low-angle thrust faults with incohesive fault rocks thicker than approximately 1 m were newly found to develop at intervals of a few km in the study area.
2. Many of these thrust faults were different from previously reported thrust faults. The thrust faults with incohesive fault rocks include clayey crush materials that form a weak and impermeable layer, which becomes the base of a DGSD and would accommodate a sliding surface of a DCL.
3. The DGSDs and rain-induced DCLs in the study area preferentially occur in the hanging walls of those thrust faults and their areal alignments are controlled by the thrust faults.
4. Thrust faults commonly extend for kilometers as planar features but are sometimes locally folded with their nearby rocks. When a syncline involving thrust faults plunges valleyward, this structure also facilitates DGSDs.