High-Resolution 3D MPM Simulation of the 2011 Akatani Landslide

The Akatani landslide, located on the Kii Peninsula of Japan, is a catastrophic deep-seated landslide triggered by intense rainfall during Typhoon Talas in 2011. The landslide mass travels a considerable distance, forming a landslide dam at the slope foot. Its instability is primarily attributed to the rapid reduction of shear strength in sandstone–mudstone (shale) materials and elevated pore water pressure. In this study, a fully three-dimensional physical model based on the Material Point Method (MPM) is applied for the first time to investigate the Akatani landslide. By employing the high-performance solver MaterialPointSolver.jl, an advanced numerical simulation is conducted, integrating geotechnical parameters from ring shear tests, pore pressure characteristics, and field-based geological and topographical data. The proposed model effectively replicates the rainfall-triggered reactivation of the landslide along pre-existing sliding surfaces identified through the Sloping Local Base Level (SLBL) ^{[1, 2]}. It captures the failure process, from initial instability to rapid downslope movement and channel blockage, under a coupled solid–fluid framework. Comparisons with field observations and previous LS-Rapid simulations demonstrate the high accuracy and applicability of this modeling approach. These findings provide essential insights for understanding the dynamic mechanisms of deep-seated rainfall-induced landslides, evaluating secondary disaster risks, and developing effective disaster mitigation strategies.

References

[1]. Chigira, M., Tsou, C. Y., Matsushi, Y., Hiraishi, N., & Matsuzawa, M. (2013). Topographic precursors and geological structures of deep-seated catastrophic landslides caused by Typhoon Talas. Geomorphology, 201, 479-493.

[2]. Jaboyedoff, M., Chigira, M., Arai, N., Derron, M. H., Rudaz, B., & Tsou, C. Y. (2019). Testing a failure surface prediction and deposit reconstruction method for a landslide cluster that occurred during Typhoon Talas (Japan). Earth Surface Dynamics, 7(2), 439-458.