Historical Co-seismic Landslides Inventory and Analysis Using Google Earth: A Case Study of 1920 M8.5 Haiyuan Earthquake, China

1000 landslides triggered by the 1920 Ms 8.5 Haiyuan Earthquake were mapped as polygons with remote sensing images provided by Google Earth. Although it was more than 90 years ago, the boundary of medium and large scale landslide triggered by the earthquake is still clear on the images. The landslides were mainly distributed in the west part of Xiji County and the southeast of Haiyuan County, which could be attributed to the difference of loess thickness. The statistical analysis results indicated that the landslide distribution was not mainly controlled by the earthquake parameters (the distance to the epicenter, the seismic intensity and the distance to the seismogenic fault rupture), but by the topographical parameters (elevation, slope height, slope gradient and slope aspect). The field surveys found that most of the landslides occurring on concave slopes of gentler than 20 degrees with long run-out and high speed may be due to the loess liquefaction.