A PRELIMINARY STUDY ON SPATIAL DISTRIBUTION PATTERNS OF LANDSLIDES TRIGGERED BY JIUZHAIGOU EARTHQUAKE IN SICHUAN ON AUGUST 8TH, 2017 AND THEIR SUSCEPTIBILITY ASSESSMENT

Abstract

A magnitude 7.0 earthquake struck Jiuzhaigou on August 8th, 2017 in Sichuan province, which is another strong earthquake happened in Sichuan province after the 2008 great Wenchuan earthquake and the 2013 Lushan earthquake. In order to provide scientific evidence for on-the-spot rescue work and geologic hazard prevention after the earthquake, the author arrived quickly on the field and finished geologic hazard interpretation and review work in the earth-stricken areas based on high resolution remote sensing images before and after the earthquake. As a result, 1833 earthquake-induced geohazards have been obtained in the study area of 840km2, which are mainly medium-scale and small-scale shallow landslides and collapses. In terms of the results of the interpretation, the spatial distribution patterns and control factors in the cosesmic geohazards (distance from the fault, PGA, elevation, slope, aspect etc.) are analyzed, the research shows that the geohazards triggered by earthquake have the features of zonal distribution mainly distributed along north-west and east-south, especially along the roads and valleys. The width of strong development zone along the field inferred seismogenic fault is about 2km, showing a distinct faulting effect, but the spatial correlation betweem geohazards and Tazang fault is weak. Based on the above-described analysis, logistic regression model is taken quick comments and divisions of geologic hazard susceptibility are made. After statists and testing, the accuracy of this model has reached 0.851, a comparatively high precise data.