Development Feature and Risk Assessment of Geological Hazards Caused by the Ms 6.2 Earthquake in Jishishan County, Linxia, Gansu Province

On December 18, 2023 at 23:59, an Ms6.2 earthquake occurred in Jishishan County, Linxia Prefecture, Gansu Province, triggering a large number of landslides and geological disasters, seriously threatening the safety of people's lives and property. This article is based on the results of on-site investigations in earthquake prone areas, conducting research on the development characteristics and risk assessment of geological disasters induced by earthquakes, and proposing suggestions for disaster prevention and reduction measures. According to on-site investigations and statistics, there are 64 new geological hazard points added after this earthquake. There are 63 potential geological hazards that have intensified. The main hidden danger points of newly added and intensified deformation are landslides, followed by landslides; The scale level is mainly small, followed by medium. Landslide geological disasters are mainly concentrated in loess hilly areas, with the main focus on building houses and roads by cutting slopes in steep loess slopes. The weighted information method based on GIS technology was used to evaluate the susceptibility of geological disasters in Jishishan County. The evaluation results showed that the proportions of high susceptibility areas, medium susceptibility areas, low susceptibility areas, and non susceptibility areas were 5.45%, 9.83%, 32.70%, and 52.02%, respectively. The high susceptibility areas were mainly distributed in the mountain ridge area of the loess hilly area in the eastern part of Jishi Mountain. On the basis of regional geological hazard susceptibility assessment, a geological hazard risk assessment of Jishishan County was conducted based on seismic activity faults, seismic motion distribution, and different rainfall conditions (10 year, 20 year, 50 year, 100 year return period). The evaluation results showed that the maximum increase in the 100 year return period extremely dangerous area compared to the 10 year return period extremely dangerous area was 18.26%, In the future, encountering extreme rainfall in the area will significantly increase the risk of geological disasters in the area. Research suggests that the post earthquake effects of geological disasters in Jishishan will be enhanced, and the frequency of landslides and collapses will increase in the future. Geological disasters are prone to form under precipitation and freeze-thaw conditions, and targeted prevention and control measures need to be taken to effectively reduce their threat level.