Development Characteristics and Inducing Factors of Geological Disasters After the Nepal"4·25"Earthquake:A Case Study of Saga County,Shigatse

YANG Xingming; SONG Jiyan; LI Chen

doi:10.13512/j.hndz.2026.01.08

Abstract：Taking the geological disasters in Saga County,Shigatse after the"4·25"M8.1 earthquake in Nepal as the research object,combined with remote sensing interpretation,field surveys,surveying and mapping,ex-ploration and experiments,this paper systematically analyzed the development characteristics of post-earthquake geological disasters and discussed their formation conditions and inducing factors.The results show that Saga Coun-ty's relatively uniform terrain and limited elevation variance restrict the diversity and scale of geological disasters.The region is primarily affected by debris flow disasters,which are closely related to the exposed bedrock and the Quaternary alluvial strata.The development and distribution of geological disasters are strongly influenced by the re-gional topography.Specifically,the area with a slope of 30° to 50° is dominated by landslides,the area with a slope of 40°to 60°is dominated by unstable slopes,and the area with a slope of 50°to 90°is dominated by col-lapse,and debris flows mainly occur in area with a slope of less than 40°.The"4·25"Nepal earthquake had a significant impact on the regional geological environment,resulting in a decrease in slope stability.The mecha-nism of earthquake-induced disasters mainly includes direct excitation and latent recurrence:direct excitation is more pronounced in areas with hard rock,while latent recurrence is more common in soft rock and loose surface rock and soil.Geological conditions are the main factors affecting the geological disasters in Saga County,followed by rainfall and human activities.The interaction among the three has jointly shaped the mechanism of geological di-sasters in the region.