Interrelated impacts of seismic ground motion and topography on coseismic landslide occurrence using high-resolution displacement SAR data

To date, a number of studies have been conducted to examine the relationship between seismic ground motion and coseismic landslides. However, the impacts of seismic ground motion on coseismic landslide occurrence are not fully understood owing to the poor spatial resolution of seismic ground motion data. Recently, seismic observation research has expanded with the use of satellite technology, as crustal deformation can be observed using pairs of SAR (synthetic aperture radar) satellite data. With this technique, obtaining information regarding the ground surface displacement induced by earthquakes is possible at a high spatial resolution, without the need for interpolation or extrapolation. In this study, we focus specifically on the interrelated impacts of seismic ground motion and topography on coseismic landslide occurrence, which has previously been difficult to detect. Using high-resolution ground surface displacement from SAR data, we examine these interrelated impacts in detail and assess coseismic landslide occurrence based on seismic ground motion and topography. Results show that the developed formula accurately reproduces coseismic landslide occurrence and that the impact behaviors of the two factors on landslide occurrence are different. Finally, based on the new formula, we suggest two different trends for the attenuation of seismic ground motion and topography related to coseismic landslide occurrence.