Physics‐Based Analysis of Aso Bridge Landslide Considering Regional‐Scale Wave Propagation Using a Multiscale SEM‐MPM Framework

Numerous case histories have demonstrated that earthquake‐induced landslides can cause significant damage to infrastructure and pose serious threats to human lives. Therefore, realistic prediction of coseismic landslides is essential for effective disaster mitigation. The multiscale SEM‐MPM method is a physics‐based numerical tool for an integrated analysis of coseismic landslides. In this study, we use the SEM‐MPM method to analyze the Aso Bridge landslide triggered by the M w 7.0 Kumamoto earthquake. The Aso Bridge landslide is located on the hanging‐wall side, with a rupture distance of less than 5 km, as one of the longest run‐out coseismic landslides. Fault rupture, regional‐wave propagation over complex topography, and local landslide failure and post‐failure behaviors of the slope are simulated. The simulation demonstrates that areas around the Aso Bridge landslide experience high‐intensity ground motions, resulting from the rupture directivity effect and topographic amplification over convex terrain. Moreover, significant velocity pulses in east‐west and north‐south directions are observed from the SEM‐MPM simulation, which may cause a long run‐out distance of the landslide. Finally, the simulation reproduces the Aso Bridge landslide in terms of run‐out distance, size, and location, thereby verifying the accuracy of the SEM‐MPM model.