Spatial Distribution Patterns of Earthquake-Induced Landslides in the Loess Region of Tongwei County, Gansu Province

This study focuses on the 1718 Tongwei earthquake (magnitude 7.5) and investigates the four counties of Tongwei, Gangu, Wushan, and Qin’an. By combining field surveys of earthquake damage and historical landslide data, we employed statistical analysis models to select ten influencing factors related to topography, geology, and seismic activity in the study area. We utilized kernel density analysis tools to statistically assess the number, area, and density of landslide points within different ranges of each influencing factor, identifying the most susceptible factor ranges for loess landslides triggered by the earthquake. The spatial distribution of these landslides under varying influences was visualized. Principal component analysis was conducted to explore the dominant factors affecting the spatial distribution of loess landslides, focusing on strongly correlated factors such as elevation, slope, and distance to rivers to further investigate their coupling effects. The results indicate that loess landslides are concentrated at elevations of 1300–1900 m, slopes of 10–20°, with a terrain fluctuation of 0–30 m, distances to rivers of 1200–1600 m, and proximity to active faults of 2–8 km, predominantly in grassland and farmland areas on south-facing slopes.