4·20芦山Ms7.0级地震地质灾害特征
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摘要
为了揭示芦山7.0级地震次生山地灾害发育规律,结合遥感解译,震后第一时间对芦山震区开展了应急调查和危险性分析等工作.芦山7.0级地震诱发的地震地质灾害以小型崩塌为主,崩塌主要沿双石-大川断裂带,北西向几个深切峡谷段,如S210芦山-宝兴峡谷,芦山-双石峡谷,芦山-太平峡谷发育,其中震中附近的宝盛、太平及龙门崩塌密度最大.崩塌源主要分布在陡立谷坡中上部、突出山嘴等部位,堆积以块石、孤石及碎石为主,对灾区的公路破坏大,其次是坡脚的民房,并在今后一段时间内,威胁公路的正常运行.潜在不稳定斜坡和土质小型滑坡,由于沟道物源的增加,震后泥石流灾害链不可忽视.地震波强度及地形放大效应是控制灾害发育的主因,斜坡结构及风化也有重要的控制作用.
In order to reveal the distribution laws of the secondary geohazards during the Lushan Ms7.0 earthquake,field investigations and interpretation of aerial photos after the earthquake were carried out to analyze the risk of the co-seismic geohazards.The results show that rockfall was the main type of the co-seismic geohazards.The rockfalls were mainly small-scaled ones and distributed along the area of the Shuangshi-Dachuan fault zone and the NW-strike gorges,such as the Lushan-Baoxing gorge,Lushan-Shuangshi gorge,and Lushan-Taiping gorge,in which the rockfalls occurred most densely in the area near the epicenter,such as Taiping,Baosheng,and Longmen.The source areas of rockfalls in the cross section of the valleys were mainly located at the middle and upper parts of a hill slope and the spur of a hill.The accumulation was mainly composed of blocks and gravel,which buried the roads,became a great risk to vehicles and houses at the toe of slopes,and would threaten the normal operation of the road in the near future.As the potential unstable slopes and small slides increase the source in the valleys and ramp during the earthquake,the debris flow would happen frequently.The PGA(peak ground acceleration) magnitude and topographic amplification was the main reason of the geohazards,and the slope structures and weathering was the second factor.
In order to reveal the distribution laws of the secondary geohazards during the Lushan Ms7.0 earthquake,field investigations and interpretation of aerial photos after the earthquake were carried out to analyze the risk of the co-seismic geohazards.The results show that rockfall was the main type of the co-seismic geohazards.The rockfalls were mainly small-scaled ones and distributed along the area of the Shuangshi-Dachuan fault zone and the NW-strike gorges,such as the Lushan-Baoxing gorge,Lushan-Shuangshi gorge,and Lushan-Taiping gorge,in which the rockfalls occurred most densely in the area near the epicenter,such as Taiping,Baosheng,and Longmen.The source areas of rockfalls in the cross section of the valleys were mainly located at the middle and upper parts of a hill slope and the spur of a hill.The accumulation was mainly composed of blocks and gravel,which buried the roads,became a great risk to vehicles and houses at the toe of slopes,and would threaten the normal operation of the road in the near future.As the potential unstable slopes and small slides increase the source in the valleys and ramp during the earthquake,the debris flow would happen frequently.The PGA(peak ground acceleration) magnitude and topographic amplification was the main reason of the geohazards,and the slope structures and weathering was the second factor.
引文
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[13]XU Q,ZHANG S,LI W L.Spatial distribution oflarge-scale landslides induced by the 5.12 Wenchuanearthquake[J].Journal of Mountain Science,2011,8:246-260.
[14]许强,李为乐.汶川地震诱发滑坡方向效应研究[J].四川大学学报:工程科学版,2010,42(增刊1):7-14.XU Qiang,LI Weile.Study on the direction effects oflandslides triggered by Wenchuan earthquake[J].Journal of Sichuan University:Engineering ScienceEdition,2010,42(Sup.1):7-14.
[15]黄润秋,李为乐.汶川地震触发崩塌滑坡数量及其密度特征分析[J].地质灾害与环境保护,2009,20(3):1-7.HUANG Runqiu,LI Weile.Analysis on the numberand density of landslides triggered by the 2008Wenchuan earthquake,China[J].Journal ofGeological Hazards and Environment Preservation,2009,20(3):1-7.
[16]李为乐.我室快速绘制雅安芦山地震次生地质灾害空间分布预测系列图件[EB/OL].(2013-04-22).http://www.sklgp.com/default.aspxid=9&subid=2&newsid=616.
[2]陶晓风.龙门山南段推覆构造与前陆盆地演化[J].成都理工学院学报,1999,26(1):73-77.TAO Xiaofeng.Evolution of nappe tectonic and forelandbasin in the southern section of Longmen mountains[J].Journal of Chengdu Institute of Technology,1999,26(1):73-77.
[3]唐荣昌,韩渭宾.四川活动断裂与地震[M].北京:地震出版社,1993:1-192.
[4]秦向辉,陈群策,谭成轩,等.龙门山断裂带西南段现今地应力状态与地震危险性分析[J].岩石力学与工程学报,2013,31(增刊):2870-2876.QIN Xianghui,CHEN Qunce,TAN Chengxuan,et al.Analysis of current geostress state ana seismic risk insouthwest segment of Longmenshan fracture belt[J].Chinese Journal of Rock Mechanics and Engineering,2013,31(Sup.):2870-2876.
[5]唐文清,刘宇平,陈智梁,等.龙门山断裂构造带GPS研究[J].大地测量与地球动力学,2004,24(3):57-60.TANG Wenqing,LIU Yuping,CHEN Zhiliang,et al.GPS study on Longmenshan fault zone[J].Journal ofGeodesy and Geodynamics,2004,24(3):57-60.
[6]李智武,刘树根,陈洪德,等.龙门山冲断带分段-分带性构造格局及其差异变形特征[J].成都理工大学学报:自然科学版,2008,35(4):440-453.LI Zhiwu,LIU Shugen,CHEN Hongde,et al.Structural segmentation and zonation and differentialacross and along the Longmen thrust belt,WestSichuan,China[J].Journal of Chengdu University ofTechnology:Science and Technology,2008,35(4):440-453.
[7]黄润秋,李为乐.汶川大地震触发地质灾害的断层效应分析[J].工程地质学报,2009,17(1):19-28.HUANG Runqiu,LI Weile.Fault effect analysis of geo-hazard triggered by Wenchuan earthquake[J].Journalof Engineering Geology,2009,17(1):19-28.
[8]张永双,雷伟志,石菊松,等.四川5.12地震次生地质灾害的基本特征初析[J].地质力学学报,2008,14(2):109-116.ZHANG Yongshuang,LEI Weizhi,SHI Jusong,et al.General character of earthquake-induced geohazardsduring 5.12 Wenchuan earthquake[J].Journal ofGeomechanics,2008,14(2):109-116.
[9]LI W L,HUANG R Q,TANG C,et al.Co-seismiclandslide inventory and susceptibility mapping in the2008 Wenchuan earthquake disaster area,China[J].Journal of Mountain Science,2013,10(3):339-354.
[10]HUANG R Q,LI W L.Analysis of the geo-hazardstriggered by the 12 May 2008 Wenchuan earthquake,China[J].Bull of Engineering Geology and theEnvironment,2009,68:363-371.
[11]HUANG R Q,LI W L.Development and distributionof geohazards triggered by the 5.12 Wenchuanearthquake in China[J].Science in China Series E:Technological Sciences,2009,52(4):810-819.
[12]GORUM T,FAN X M,WESTEN C J,et al.Distribution pattern of earthquake-induced landslidestriggered by the 12 May 2008 Wenchuanearthquake[J].Geomorphology,2011,133(3/4):152-167.
[13]XU Q,ZHANG S,LI W L.Spatial distribution oflarge-scale landslides induced by the 5.12 Wenchuanearthquake[J].Journal of Mountain Science,2011,8:246-260.
[14]许强,李为乐.汶川地震诱发滑坡方向效应研究[J].四川大学学报:工程科学版,2010,42(增刊1):7-14.XU Qiang,LI Weile.Study on the direction effects oflandslides triggered by Wenchuan earthquake[J].Journal of Sichuan University:Engineering ScienceEdition,2010,42(Sup.1):7-14.
[15]黄润秋,李为乐.汶川地震触发崩塌滑坡数量及其密度特征分析[J].地质灾害与环境保护,2009,20(3):1-7.HUANG Runqiu,LI Weile.Analysis on the numberand density of landslides triggered by the 2008Wenchuan earthquake,China[J].Journal ofGeological Hazards and Environment Preservation,2009,20(3):1-7.
[16]李为乐.我室快速绘制雅安芦山地震次生地质灾害空间分布预测系列图件[EB/OL].(2013-04-22).http://www.sklgp.com/default.aspxid=9&subid=2&newsid=616.
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