On December 18, 2023, an Ms6.2 earthquake occurred in Jishishan County, Gansu Province. The co-seismic geological hazards induced by the earthquake seriously threaten the safety of personnel and property. It is very important and urgent to summarize and analyze the development law of co-seismic geological hazards and the assessment of county susceptibility in time to support post-earthquake recovery and reconstruction. Through emergency investigation and field investigation and result analysis, it is found that the overall development degree of co-seismic geological hazards in the earthquake area is not strong, and the scale is mainly small, which is 3 categories and 8 sub-categories of hidden dangers of landslides, most of which are distributed in the loess hilly area. Based on the Pearson correlation coefficient and random forest Gini coefficient analysis method, 15 influencing factors were selected, and the random forest model was used to assessment the susceptibility of co-seismic geological hazards in Jishishan County (AUC = 0.961). The results show that the area of extremely high susceptibility area accounts for about 8.67%, mainly distributed in Hulinjia Township, Xuyijia Township, Liugou Township and other townships, and the susceptibility classification structure of counties and townships is consistent with the density distribution of hidden danger points, with high accuracy. Based on this, the purpose of predicting the spatial distribution of potential geological hazards other than the hidden danger points is realized to a great extent, which can provide zoning support for the post-disaster recovery and reconstruction planning of Jishishan County.
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