地震地质 ›› 2020, Vol. 42 ›› Issue (1): 125-146.DOI: 10.3969/j.issn.0253-4967.2020.01.009

• 研究论文 • 上一篇    下一篇

2008年MS 8.0汶川地震诱发滑坡灾害在映秀地区的演化特征

兰剑, 陈晓利   

  1. 中国地震局地质研究所, 活动构造与火山重点实验室, 北京 100029
  • 收稿日期:2019-06-19 修回日期:2019-08-20 出版日期:2020-02-20 发布日期:2020-06-17
  • 通讯作者: 陈晓利,女,1969年生,研究员,主要从事地震地质灾害研究工作,E-mail:chenxl@ies.ac.cn。
  • 作者简介:兰剑,男,1994年生,现为中国地震局地质研究所构造地质专业在读硕士研究生,主要从事地震地质灾害研究,电话:18500237763,E-mail:lanjian@ies.ac.cn。
  • 基金资助:
    国家重点研发计划项目"强震区特大地质灾害致灾机理与长期效应研究"(2017YFC1501004)资助

EVOLUTION CHARACTERISTICS OF LANDSLIDES TRIGGERED BY 2008 MS8.0 WENCHUAN EARTHQUAKE IN YINGXIU AREA

LAN Jian, CHEN Xiao-li   

  1. Institute of Geology, China Earthquake Administration, Key Laboratotry of Active and Volcano, Beijing 100029, China
  • Received:2019-06-19 Revised:2019-08-20 Online:2020-02-20 Published:2020-06-17

摘要: 强烈的地震不仅能够在山岳地区触发大量的同震滑坡,对震后灾区地质灾害的发育水平也存在重要影响。因此,研究地震滑坡的演化特征对于强震区地质灾害防治具有重要作用。文中以2008年MS8.0汶川地震震中附近受到强震扰动的映秀为研究区,通过对该区域(面积约66km2)震前1期(2005年4月)、震后5期(2008年6月、2011年4月、2013年4月、2015年5月和2017年5月)的高分辨率影像进行滑坡解译和编录,借助GIS平台,获取了高程、坡度、坡向、曲率、地层岩性、距最近水系的距离和距发震断裂的距离这7个主要因子的数据,研究地震滑坡的长期演化特征;同时,应用相关分析方法对比了不同时期的滑坡活动性强度,对该区域内汶川地震诱发的滑坡灾害的演化规律进行了研究。结果表明,2008-2017年,研究区内的滑坡总面积急剧减少,同震滑坡面积从21.41km2降低到1.33km2,表明震后滑坡的灾害活动程度已经恢复或接近震前水平。整体而言,研究区内滑坡的规模不断减小,滑坡活动性随着时间减弱,再活动滑坡和新增滑坡数量也相应减少。滑坡灾害体面积减少的区域主要集中在高程为1 000~2 100m、坡度为30°~55°、坡向为40°~180°、曲率为-2~2的区域。此外,汶川地震映秀研究区中的彭灌杂岩体环境更利于滑坡的产生,而沉积碎屑岩岩性更利于滑坡活动性的恢复。距最近水系的距离>1 600m时,水系对滑坡的影响作用逐渐减小,且研究区地震滑坡存在上盘效应,即断裂西北地区的滑坡数量远多于东南一侧。

关键词: 强震区灾害, 演化规律, 汶川地震, 地震滑坡, 相关分析

Abstract: Strong earthquakes can not only trigger a large number of co-seismic landslides in mountainous areas, but also have an important impact on the development level of geological hazards in the disaster area. Usually, geological hazards caused by strong earthquakes will significantly increase and continue for a considerable period of time before they recover to the pre-earthquake level. Therefore, studying the evolution characteristics of landslides triggered by earthquake is particularly important for the prevention of geological disaster. In this paper, a 66km2 region in Yingxiu near the epicenter of the 2008 MS8.0 Wenchuan earthquake, which was strongly disturbed by the earthquake, was investigated. Firstly, one high-resolution satellite image before the earthquake(April, 2005) and five high-resolution satellite images after the earthquake(June, 2008; April, 2011; April, 2013; May, 2015; May, 2017)were used to interpret and catalog multi-temporal landslide inventories. Secondly, seven primary factors were analyzed in the GIS platform, including elevation, slope, aspect, curvature, stratum, lithology, and the distance from the nearest water system and the distance from seismogenic faults. Finally, the evolution of the landslide triggered by earthquake in this region was analyzed by comparing the landslide activity intensity in different periods, using the methods of correlation analysis, regression analysis, and single-factor statistical analysis. It was found that the total area of landslides in the study region decreased sharply from 2008 to 2017, with the area of the co-seismic landslide reducing from 21.41km2 to 1.33km2. This indicates that the magnitude of the landslides has recovered or is close to the pre-earthquake level. Moreover, correlation analysis shows that the elevation has a strong positive correlation with the distance from the nearest water system, and a weak positive correlation with the area. Meanwhile, there is a weak negative correlation between the distance from the nearest water system and the distance from seismogenic faults. Overall, the degree of landslide activity in the study region decreased over time, as well as the number of reactivated landslides and new landslides. The region where the area of earthquake triggered landslides decreased mainly concentrated at an elevation of 1 000m to 2 100m, a slope of 30° to 55°, an aspect of 40° to 180°, and a curvature of -2 to 2. In addition, the lithology of the Pengguan complex in the Yingxiu study region is more conducive to the occurrence of landslides, while the sedimentary rock is more conducive to the landslide recovery. When the distance from the nearest water system is more than 1 600m, the effect of the water system on the landslides gradually decreases. Also, the landslides triggered by Wenchuan earthquake in this area have the characteristics of the hanging wall effect, which means, the number of landslides in the northwestern region is much higher than that in the southeast side.

Key words: geohazard in strong earthquake area, evolution pattern, Wenchuan earthquake, earthquake-triggered landslides, correlation analysis

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