Controlling role of ground motion time histories on the north‒south difference in coseismic landslide distribution during the 2018 Hokkaido Eastern Iburi earthquake

Abstract

Earthquake-triggered landslides are known to exhibit unique regional characteristics that can cause extensive damage to the environment, resulting in a significant loss of life and property. This study aims to comprehensively investigate the role of ground motion time histories in shaping the unique distribution of coseismic landslides during the 2018 Hokkaido Eastern Iburi earthquake. Despite the similar geological and geomorphological conditions on the northern and southern sides of the epicenter, landslide density was notably higher on the northern side. In our workflow, we conducted nonlinear dynamic finite difference simulations of slope stability to reproduce the actual landslide distribution pattern using synthetic waveforms. We discuss the controlling role of ground motion time histories on these coseismic landslides. The study reveals that differences in phase components were responsible for the varying deformation processes of slopes under seismic loading, ultimately leading to the observed differences in landslide distribution. Moreover, the study emphasizes that energy-based seismic intensity measures carry greater significance than amplitude-based intensity measures because they consider the entire ground motion time histories rather than focusing solely on peak values at specific moments. The proposed method outlined in this study can be applied to regional landslide hazard analysis and risk assessment for future earthquakes.