The effect of location and geometric properties of landslides caused by rainstorms and earthquakes

Abstract

Landslides triggered by rainstorms and earthquakes are prominent geological hazards that exhibit distinctive spatial and morphological characteristics due to diverse instability mechanisms. However, studies on differences between the two types of landslides remain limited. In this study, we explored differences in location and geometric properties between rainstorm-induced landslides in Qinzhou, Longchuan and Fukuoka and earthquake-induced landslides in Lushan, Iburi and Kaikōura. We normalized the location of landslides across the slope and quantified the landslide polygons using four geometric properties. Findings revealed that both location and geometric properties are specific to landslide type and differ between them. Earthquake-induced landslides are more common near the ridge of a slope, while rainstorm-induced landslides are more frequent in the valley or near streams. The quantitative analysis of geometric properties showed that earthquake-induced landslides are generally larger and have a more compact, rounded and less complex shape. The two landslide types present different hazards, particularly in their runout zones, where dispersion of materials occurs. Insights from our quantitative approach serve as a critical foundation for informed decision-making in emergency scenarios and contribute to enhancing landslide hazard management.