A new index representative of seismic cracks to assess post‐seismic landslide susceptibility

Abstract

AbstractIn a major earthquake, strong shaking reduces the natural soil strength. Therefore, evaluation of the susceptibility of post‐seismic landslides may help prevent further disasters in an affected area. This study developed an index representing the spatial density of seismic cracks—the dense crack index (DCI)—to express the degree of local ground effects. An area of 6 km2 with 196 slides identified after the 2016 Kumamoto earthquake (Mw 7.0) was analyzed using models that incorporated the weight of evidence (WoE), logistic regression, and random forest (RF) methods, with the DCI as a conditioning factor. The WoE and RF models confirmed the importance of the DCI, although the improvement in performance as indicated by area under the curve values was marginal or negligible. This was largely due to combinations of other factors that enabled inclusion of locations with strong seismic waves, which compensated for the absence of the index. The contribution of the DCI could be improved if more accurate LiDAR data were used in the analysis.