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

This paper takes Tongwei County, Gangu County, Wushan County and Qin'an County counties involved in the 1718 Tongwei M7.5 earthquake as the study area. Elevation, The slope, aspect, topographic relief, lithology, land use type, vegetation coverage, distance to river, intensity, distance to active fault, residential density and distance to road, which are related to topographic, geological, seismic and human activities factors, are selected to analyze the spatial distribution law of loess earthquake-induced landslides in the study area. Firstly, based on GIS platform, the selected 12 factors are classified according to the geographical characteristics of the study area itself, and then the number, area and corresponding density of landslide points in different grade intervals of each factor are counted by kernel density analysis tool, so as to extract the most vulnerable factor intervals of loess seismic landslides. The spatial distribution of earthquake-induced loess landslides in Tongwei area under the influence of different factors is displayed in a visual way. Finally, the relative contribution and coupling effect of these factors on the spatial distribution of earthquake-induced loess landslides are discussed by using the principal component analysis method. The results show that the spatial distribution of earthquake-induced loess landslides in Tongwei area is affected by many factors, among which topographic relief, slope and intensity are the most important factors. Earthquake-induced loess landslides in the study area are mainly distributed in the southward slope area with a slope of 10-20 °, a topographic relief of 0-30 m, a distance of 2-8 km from the active fault, an intensity of X and a loose loess layer. In addition, the study also shows that human activities have a certain impact on the spatial distribution of earthquake-induced loess landslides, and the number of landslides is significantly higher in the areas close to residential areas and roads. The spatial distribution law of earthquake-induced loess landslides in Tongwei area obtained in this study can not only provide a theoretical basis for earthquake prevention and disaster reduction in Tongwei area, but also provide an effective treatment direction for the areas with high incidence of landslides.