Fast report: preliminary analysis of coseismic landslides in the 2025 M6.4 Dapu earthquake

Abstract After the 2025 M6.4 Dapu earthquake, the Agency of Rural Development and Soil and Water Conservation (ARDSWC) identified 29 coseismic landslides using Sentinel-2 and PlanetScope satellite imagery. Two-thirds of these landslides occurred south of the epicenter, indicating a likely southward rupture. These landslides are found to (1) locate in areas where PGA exceeded 250 cm/s 2 and PGV over 17 cm/s (2) occur on 30° to 50° slopes, often on southeast- to southwest-facing aspects. Dip slopes and the reactivation of historical landslides were key contributing factors. Although satellite imagery detected fewer landslides than other earthquakes with comparable magnitude, our field surveys revealed numerous fresh landslide scarps in areas with PGA over 400 cm/s 2 and PGV around 30 cm/s. Our analysis provides useful information of coseismic landslide behaviors and the triggering factors in the Dapu event. These findings highlight the importance of detailed post-earthquake landslide mapping and field investigations, which provides key information for advanced hazard mitigation plans for seismically affected regions in preparation for the upcoming rainy season.