| The seismic landslide disaster is the most powerful earthquake secondary disaster which has long posed a great threat to the safety of life and property in China.The northeastern margin of the Tibet Plateau is one of the areas with the most severe earthquake,and also one of the most serious landslide disaster areas in China.A large number of co-seismic landslides were triggered by the Gulang M8.0 earthquake of 1927,which occurred at the junction of the Loess Plateau and the northeastern margin of the Tibet Plateau.But there are very few systemic and comprehensive results about the landslides that triggered by this earthquake.This situation hinders the deep understanding of the scientific issues such as the scale,extent and distribution of the landslides triggered by the Gulang earthquake.Based on the high-resolution satellite image of Google Earth and ArcGIS platform,combined with topographic,geological and seismic data,high impact area of Gulang earthquake(VIII?XI degree)was deeply studied.The results of this paper provide a scientific reference for further understanding the development law of Gulang earthquake landslide in 1927 and reducing the earthquake landslide disaster.The results are as follows:(1)Based on the 3D view of Google earth platform and the interpretation method of historical seismic landslides,we have carried out the artificial visual interpretation of Gulang seismic landslides.And the detailed landslide cataloging map of Gulang earthquake area of 1927,containing 936 seismic landslides,was obtained.The total area of the landslide is 58.6km2.The landslide is mainly medium and small.The landslide intensive area is located in the middle and south of the X intensity circle.The landslide point density and the percentage of landslide area in the study area are 0.075 ·km-2 and 0.47%.(2)We select ten factors,which is elevation,slope,aspect,TPI,the distance from river,strata,the distance to epicenter,the distance to fault,seismic intensity and peak ground acceleration(PGA),with the help of the number of landslides,landslide area,point density and landslide area percentage four index analysis to study the distribution of seismic landslide spatial pattern,The results are compared with previous research results and discussed.The statistical analysis shows that the elevation of 2000?2800m is the high prone region of landslide.Landslides mainly occur on middle and low slopes,and the higher the slope is,the higher the landslide density is.East-west and NE-SW are the dominant sliding directions of the landslide.The Cretaceous and Quaternary strata are the main strata for Gulang earthquake landslide.X intensity region produces the largest landslide scale;Landslides are more likely to occur the closer they are to faults and rivers.As the results of landslides distribution are more detailed,some phenomena that were not revealed in previous studies have been discovered.(3)Based on ArcGIS and SPSS software,the logistic regression model was used to evaluate the landslide risk,and the evaluation results of the susceptibility in the study area were divided into extremely low risk area,low risk area,medium risk area,high risk area and extremely high risk area,and the evaluation results of the landslide risk in the study area were obtained.The ROC curve was used to evaluate the accuracy of the risk,and the result was that the AUC of the logistic regression model was 0.964,indicating that the accuracy of the evaluation results of the model was high and the evaluation results were relatively ideal.Based on the established model,the seismic landslide hazard distribution maps of different levels of peak ground motion acceleration in the study area were obtained. |
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