2017年8月8日四川省九寨沟MS7.0地震触发滑坡全景

摘要

2017年8月8日的四川省九寨沟县MS7.0地震触发了大量滑坡.全面客观地获取地震滑坡发生全景,对于理解地震滑坡宏观机制、发育强度、分布样式与规律,灾区恢复重建与滑坡防灾减灾具有重要意义.文中利用天、空、地相结合的手段,获取本次地震触发滑坡全景.同震滑坡主要分布区内有4条公路,沿线同震滑坡最严重的为金铃海—夏莫段与九道拐—九寨天堂段.类型以中型与小型破碎型滑坡为主,也有少量的大型滑坡与碎屑流.开展了有0.2m 超高分辨率震后航片覆盖的五花海区域(11.84km2)与扎如寺—上四寨村沿线(47.07km2)的滑坡分布详细调查.结果表明,受发震断层的影响,五花海区域的同震滑坡发育程度(1088处滑坡,总面积1.514km2)远高于扎如寺—上四寨村沿线(528处滑坡,总面积0.415km2).基于 Geoeye-1震后影像开展了极震区同震滑坡解译,得到本次地震触发的超过4800处滑坡,总面积约9.6km2,这些滑坡在空间上与推测发震断层位置、余震分布具有良好的对应关系.震区发育的强度弱化斜坡、悬停在高坡位的堆积体与停留在沟谷中的滑坡松散堆积体,后续在强余震或强降雨条件下再次失稳并形成新的滑坡与泥石流的可能性较大,滑坡与泥石流等地质灾害问题将成为震后恢复重建面临的最重要问题之一.%The MS7.0 Jiuzhaigou earthquake in Sichuan Province of 8 August 2017 triggered a large number of landslides.A comprehensive and objective panorama of these landslides is of great significance for understanding the mechanism,intensity,spatial pattern and law of these coseismic landslides, recovery and reconstruction of earthquake affected area,as well as prevention and mitigation of landslide hazard.In this paper,we use the trinity method of space,sky and earth to create a panorama of the landslides triggered by this event.There are 4 roads in the distribution area of the coseismic landslides.The Jinglinghai-Xiamo and Jiudaoguai-Jiuzhaitiantang road sections register the most serious coseismic landslides.The landslides are mainly of moderate- and small-scales,and also with a few large landslides and avalanches.A detailed visual interpretation of the coseismic landslides is performed in two areas of Wuhuahai(1 1.84km2)and Zharusi-Shangsizhai village(47.07km2), respectively.The results show the overall intensity of landsliding(1088 landslides,a total area 1.5 14km2)in the Wuhuahai area is much higher than those in the Zharusi-Shangsizhai village area (528 landslides,a total area 0.415km2).On the basis of a scene of post-earthquake Geoeye -1 satellite images,we delineate more than 4 800 coseismic landslides with a total occupation area 9.6km2.The spatial pattern of these landslides is well related with the locations of the inferred seismogenic fault and aftershocks.Widely distributed earthquake-affected weakened slopes,residual loose materials staying at high-position slopes and in valleys have greater possibilities to fail again and generate new landslides or debris flows under the conditions of strong aftershocks or heavy rainfalls in the future.Geological hazard from these events will become one of the most serious problems in the recovery and reconstruction of the earthquake-affected area which should receive much attention.