Hazard assessment on secondary mountain-hazards triggered by the Wenchuan earthquake

The Wenchuan earthquake triggered large numbers of secondary mountain hazards which caused great casualties and losses. Based upon remote sensing interpretation, field investigation, and disaster surveys, we describe the general situation of the earthquake, study the spatial distribution of the secondary mountain hazards, establishe a hazard degree index model according to disaster-forming factors and seismic parameters, and make a hazard assessment on the secondary mountain hazards. Moreover, using geographical information system and remote sensing technologies and the principle of regional factors, the study area is classified into four hazard zones: no-hazard zone, low-hazard zone, moderate-hazard zone, and high-hazard zone. The results show that the high-hazard zone is distributed along the three main fault zones of the Longmen Mountain, mainly along the Minjiang River valley, the Yuzi Creek, the Jianjiang River valley, and other river valley areas. The other hazard zones are distributed outside the high-hazard zone in a ring shape, respectively, and their hazard degrees decrease gradually, especially in the low elevation areas and the Chengdu Plain where the hazard degree is the lowest. The developmental trend of secondary mountain hazards is analyzed in view of geodynamics.