Preliminary analysis of the coseismic geohazards induced by the 2023 Jishishan Ms 6.2 earthquake
On December 18,2023,an earthquake with a magnitude of Ms 6.2 occurred in Jishishan County,Gansu Province,triggering a large number of coseismic geohazards.As such,there is an urgent need to identify the characteristics,distribution patterns,and mechanisms of the coseismic geohazards caused by this earthquake to provide support for post-earthquake recovery and reconstruction.Based on multisource high-resolution remote sensing interpretation and a comparative analysis of existing research results,the essential characteristics and distribution patterns of the coseismic geohazards are preliminarily revealed,and the mechanism of the liquefaction landslide mudflow in Caotan Village is explored.The results show that a total of 1 535 coseismic geohazards developed in areas with a seismic intensity of Ⅶ or above during the earthquake,mainly consisting of small-and medium-scale loess landslides and shallow rockfalls.These geohazards were mainly distributed on both sides of loess beams and loess plateau gullies,on both sides of thin loess beams,and on the back walls of large historical landslides where the terrain was steep.It is found that earthquake factors controlled the regional distribution pattern of coseismic geohazards,while terrain factors controlled the local distribution pattern of coseismic geohazards.We find that the coseismic geohazards had the highest distribution in areas of peak acceleration of 0.1-0.3 g,footwall areas around the seismic fault,areas where the slope points in a southeastern direction,areas with slope heights of 30-60 m,and areas 20-40 m above the middle of the slopes.The sand surge disaster in Caotan Village,which caused great concern throughout all of society,was a liquefaction landslide caused by saturated loess reacting to earthquake action.This disaster may be have been inadvertently exacerbated by the"gully filling and land reclamation project"that completed in 2016,which changed the surface and groundwater flow conditions in the sliding source area.Additionally,groundwater channels were blocked,causing the groundwater level to rise and the lower soil to saturate,which may be an essential reason for the liquefaction landslides in this area.
Jishihan earthquakecoseismic geohazardsdistribution patternloess landslideliquefied landslide-mudflow gully filling and land reclamation project