Spatial Distribution And Geometrical Characteristic Of Landslides Related To The 2013 Minxian Earthquake Of Gansu Province

An earthquake of Mw5.9 (Ms6.6) happened in 2013 on the boundary of Minxian and Zhangxian County in Gansu Province. Based on GIS and Google Earth platform, with the help of high resolution satellite remote sensing images and DEM data with resolution of 5 meter, the objective and comprehensive earthquake-induced landslide inventory had been established by artificial visual interpretation in the struck area of 873.95km2. The landslide number, size and geometry characteristics were analyzed, and the regional landslide spatial distribution, the distribution of geometric shape and the spatial distribution of different morphological landslides were obtained. Specifically, the main results are as follows:1. By comparing the high resolution satellite remote sensing images obtained before and after the earthquake, there are 6478 coseismic landslides had been registered, and the total area of these landslides are 1.71km2. Among which, the number of landsides with area larger than 100m2 are 3322, and for landslides with area larger than 500m2 are 635.2. Factors of elevation, slope, aspect, curvature, slope position, distance from drainages, lithology, seismic intensity, peak ground acceleration (PGA) and distance from the seismogenic fault were selected. On the base of landslide number density and landslide area density, and 3322 landslides of area larger than 100 m2 were used to analyze the landslide spatial distribution.3. With landslides whose area are largest than 500m2 as the research objects, based on the GIS platform, the length, width and height of these landslides were extracted, and the geometric features of the coseismic landslides were analyzed with parameters of height-length ratio and length-width ratio.According to the length-width ratio, these landslides in the research area had been divided into 4 classes:transverse landslide (L/W≤0.8), isometric landslide (0.8<L/W≤1.2), longitudinal landslide (1.2≤L/W≤3) and elongated landslide (L/W>3). By analyzing the relationship between different types of landslide and the influence factors, the geometric characteristic distribution of landslides were obtained.