汶川地震引发的次生灾害链

汶川地震造成了大量的滑坡、崩塌,并诱发了多种地质和生态灾害链式发生.2008-2009年期间,在汶川地震震区开展了野外调查与试验,研究了各种不同的灾害链的形成条件及其链生机制.识别出了4种类型的灾害链,并重点研究了7起灾害链事件.发现灾害链中,每一级灾害事件都由其前一级灾害事件诱发.各级次生灾害造成的物质搬运量都远小于其上一级灾害所造成的物质搬运,灾害性沿灾害链呈现逐级衰减的趋势.由此定义灾害链衰减率为灾害链中某级次生灾害所造成的物质搬运或者灾害影响区面积与其上一级灾害所造成的物质搬运或灾害影响区面积之间的比值.汶川地震引起的次生灾害链衰减率在2％～30％.采用底栖动物作为指示物种,评价次生灾害链对震区河流生态造成的影响,发现受灾害链影响的河道中,底栖动物物种数急剧降低,生物多样性下降.

Disaster Chains Initiated by the Wenchuan Earthquake

The Wenchuan Earthquake caused numerous landslides and avalanches,which initiated causal chains of secondary disasters.Field investigations and field experiments were performed in the earthquake area during 2008—2009 to study the disaster chains.Four types of disaster chains have been identified.In all of these disaster chains,each episode was caused by the previous episode.Moreover,the amount of mass movement decreased along the disaster chains.This paper defined an attenuation factor of disaster chain,which is expressed as the ratio of the volume of mass movement or affected area in one episode of a chain to the volume or affected area in the causal episode to express the decreasing.The attenuation factor of disaster chains caused by the Wenchuan Earthquake ranges from 2% to 30%.Macroinvertebrates were used to evaluate the ecological effect of the disaster chains,and it found that the species taxa were greatly reduced in the affected reach.