“4·20”芦山Ms7.0级地震次生山地灾害特征

北京时间2013年4月20日08时02分,在四川省雅安市芦山县发生7.0级大地震.大地震同时诱发大量滑坡、崩塌等同震次生山地灾害.据现场应急调查,地震次生山地灾害主要以中小规模崩塌灾害为主,根据灾害发生的地层岩性,分别归纳了砾岩地层崩塌、砂泥岩地层崩塌、灰岩直立地层崩塌、堆积层滑坡及滑坡碎屑流5个主要类型.在对典型灾害体灾害特征、破坏模式和影响因素进行初步分析的基础上,提出区域构造背景为“4·20”芦山地震次生灾害的主控因素.芦山地震次生灾害具有群发性、滞后性特点,在后地震时期降雨激发条件下可能产生严重泥石流滑坡等山地灾害.因此,后地震时期在极震区特别是集中安置区,山地灾害监测预警工作十分重要.

Features of Secondary Mountain Hazards Triggered by the 4.20 Lushan Earthquake

Ms 7.0 giant earthquake took placed in Lushan County, Yaan City at 8:02, April 20th, 2013, which claimed 196 of lives, 21 of missing and effected 2M people, also induced large amount of secondary mountain hazards including collapses, landslides, etc. The most of secondary mountain disasters is collapses with small and median scale volume according to field investigation. Five principal types of secondary mountain disasters consisting of conglomerate collapses, sandstone collapses, carbonate stone collapses, landslides and long run-out landslide-avalanche were proposed and the characteristics, mechanism and influence factors were analyzed. The regional geological environment and structure was regarded as the primary element through preliminary analysis, and the large amount of loosen materials are easy for occurring debris flows and landslides triggering by the storm and continuous rainfall, which will seriously threat the reconstruction and lives in the rainy season for decades, therefore the post-earthquake effect as well as the monitoring and pre-warning strategy should be carry out in meizoseismal area and especially in reconstruction settlements.