四川九寨沟Ms7.0级地震滑坡应急快速评估

基于地震滑坡危险性评估的Newmark累积位移模型,利用震前获取的震区地形数据、区域地质资料,结合地震动近实时获取技术,开展了四川九寨沟M_s7.0级地震诱发滑坡的应急快速评估。地震滑坡位移分析结果表明,同震滑坡活动的中—高强度区分布在断层两侧宽约4 km的带状区域内,整体沿北西方向延伸。其中,极震区的丰雪塘、日则和干海子等城镇驻地及附近道路的滑坡强度相对较高;震前、震后影像对比表明九寨沟地震诱发的滑坡类型以浅表型碎屑流及小规模崩塌为主,且同震碎屑流多是在震前已有碎屑流的基础上进一步活动扩展而来,震后汛期泥石流隐患也不容忽视;通过典型地区滑坡位移分析结果与震前、震后影像对比,表明滑坡位移分析结果能够较好的反映同震滑坡的宏观分布特征,但在场地尺度上吻合程度欠佳,后续将通过提升岩性和地形等数据质量进行改进。研究结果可为灾情研判提供宝贵信息,对提高灾害应急救援效率具有重要意义。

EMERGENCY RAPID ASSESSMENT OF LANDSLIDES INDUCED BY THE JIUZHAIGOU MS 7.0 EARTHQUAKE, SICHUAN, CHINA

Based on the Newmark cumulative displacement model, emergency rapid assessment of earthquake landslides induced by the Sichuan Jiuzhaigou M_s 7.0 earthquake was carried out based on regional topographic and geologic data, combined with near-real-time estimates of ground shaking. The analysis results of seismic landslide displacements show that the medium-high risk zones of coseismic landslide activities are mainly concentrated in the area about 4 km width along the seismogenic fault, with a roughly NW-SE rift direction, especially in the Fengxuetang, Rize, and Ganhaizi town of the meizoseismal area. Comparison between the satellite images acquired before and after this earthquake shows that the most common types of landslides induced by the Jiuzhaigou earthquake are shallow debris flows and small scale of rock falls, and the shallow debris flows are mostly formed by the further expansion of activities of the existing landslides. It shows that the obtained displacements can well reflect the macro distribution of coseismic landslide, but they can''t be exerted effectively at local site scale, which can be enhanced through the improvement of large scale of geologic maps and high quality topography data. Results can provide valuable timely reference information on the possible societal effects of earthquake-induced landslides.