Abstract:
At 8:02 am, 20 April 2013, the Ms 7.0 Lushan earthquake struck the southern area of the Longmen Mountain on the eastern margin of the Tibetan Plateau in Sichuan Province. A lot of geohazards followed this earthquake. Taking the hazards-prone Baoxing area as the study area and based on the remote sensing analysis, digital elevation model, statistic analysis and field investigation, the authors analyzed the distribution of the geohazards and the relationship between hazards and lithology, faults and slope gradient and, on such a basis, summarized the features of seismic geohazards in the Baoxing area: ①Hazards are mostly small or medium-sized collapses and landslides, and are mostly distributed along road S210. ②Collapses and landslides mainly occur in the highly weathered layers of the Baoxing complex and Quaternary superficial layer. ③Wulong and Xiaoguanzi faults are not coseismic faults of Lushan earthquake. ④In the study area, 70% of collapses and landslides occur in the areas whose slope is steeper than 30°, and the slope of most geohazards range from 30° to 40°. ⑤Human engineering activity is the main controlling factor of the geohazards distributed along road S210. ⑥Because the slopes impacted by the Wenchuan and Lushan earthquakes become very unstable, landslides, collapses and debris flow are more prone to occur, and hence the coming several years will be the high-incidence period.