汶川地震高烈度区暴雨滑坡活动的遥感动态分析
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摘要
强烈地震作用对山地斜坡稳定性影响是长期的,汶川地震不仅直接诱发了大量滑坡,而且在后继的强降雨过程中大大加速了震区滑坡的活动性.以汶川地震高烈度区的北川县城及湔江河谷为研究区,利用高精度航空图像解译出1214处不同类型的滑坡.地震后的2008年9月24日暴雨过程诱发了更多的滑坡和泥石流,这场20年一遇的强降雨的累积雨量为272.7mm.基于SPOT5遥感影像解译,共发现新增的暴雨滑坡823处.根据"9.24"暴雨前后的遥感解译结果对比,研究区暴雨诱发的滑坡数量增加了68%,滑坡面积扩大了46.6%,这种现象表明强震后暴雨对滑坡发育和活动影响十分明显.研究结果也说明汶川震区在强降雨作用下极易发生滑坡和泥石流.
A catastrophic earthquake always intensively disturbs ground strata and affects the slope stability for a long period of time.The Wenchuan earthquake not only triggered serious coseismic landslides,but also extensively accelerated the landslide activity during the subsequent heavy rains.Based on the interpretation of high resolution of aerial photographs,1 214 landslides are identified,most of which are shallow landslides,rock falls,and rock slides triggered in the high seismic intensity region of the Wenchuan earthquake near the Beichuan City and along the valleys of the Jianjiang River.A heavy rainfall on 24 September,2008 triggered more landslides and debris flows in the central part of the area affected by the Wenchuan earthquake.The accumulated precipitation triggering landslides and debris flows is 272.7 mm in two days,while the rainfall amount and intensity recorded in this area have a return period of about 20 years.878 new landslides in the study area of 340 km2 are identified by interpretation of SPOT images.To understand the impact of the Wenchuan earthquake on the landslide occurrence due to subsequent heavy rainfall,this study mainly focuses on the variations in the the density of coseismic landslides and following rainfall-induced landslides through aerial photographs and SPOT images.Comparison of aerial photographs taken on 18 May,2008 (after the "5·12" Wenchuan earthquake) and SPOT images taken on 14 October,2008 (after "9·24" rainstorm event) indicates that the landslide number in the study area increases by 42%,while landslide area increases by 46.6%,which shows the great impact of the heavy rainfall after the earthquake on the development and activity of landslides in the study area.The above study results also show that the Wenchuan earthquake affected area is particularly susceptible to landslides and debris flow occurrence after extreme rainfall events.
A catastrophic earthquake always intensively disturbs ground strata and affects the slope stability for a long period of time.The Wenchuan earthquake not only triggered serious coseismic landslides,but also extensively accelerated the landslide activity during the subsequent heavy rains.Based on the interpretation of high resolution of aerial photographs,1 214 landslides are identified,most of which are shallow landslides,rock falls,and rock slides triggered in the high seismic intensity region of the Wenchuan earthquake near the Beichuan City and along the valleys of the Jianjiang River.A heavy rainfall on 24 September,2008 triggered more landslides and debris flows in the central part of the area affected by the Wenchuan earthquake.The accumulated precipitation triggering landslides and debris flows is 272.7 mm in two days,while the rainfall amount and intensity recorded in this area have a return period of about 20 years.878 new landslides in the study area of 340 km2 are identified by interpretation of SPOT images.To understand the impact of the Wenchuan earthquake on the landslide occurrence due to subsequent heavy rainfall,this study mainly focuses on the variations in the the density of coseismic landslides and following rainfall-induced landslides through aerial photographs and SPOT images.Comparison of aerial photographs taken on 18 May,2008 (after the "5·12" Wenchuan earthquake) and SPOT images taken on 14 October,2008 (after "9·24" rainstorm event) indicates that the landslide number in the study area increases by 42%,while landslide area increases by 46.6%,which shows the great impact of the heavy rainfall after the earthquake on the development and activity of landslides in the study area.The above study results also show that the Wenchuan earthquake affected area is particularly susceptible to landslides and debris flow occurrence after extreme rainfall events.
引文
Chen,H.,Hawkins,A.B.,2009.Relationship betweenearthquake disturbance,tropical rainstorms and debrismovement:an overviewfrom Tai wan.Bull.Eng.Geol.Environ.,68(2):161-186.doi:10.1007/s10064-009-0209-y
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Kamp,U.,Growley,B.J.,Khattak,G.A.,et al.,2008.GIS-based landslide susceptibility mapping for the2005Kashmir earthquake region.Geomorphology,101(4):631-642.doi:10.1016/j.geomorph.2008.03.003
Lin,C.W.,Liu,S.H.,Lee,S.Y.,et al.,2006.I mpacts ofthe Chi-chi earthquake on subsequent rainfall-inducedlandslides in central Tai wan.Engineering Geology,86(2-3):87-101.doi:10.1016/j.enggeo.2006.02.010
Lin,C.W.,Shieh,C.L.,Yuan,B.D.,et al.,2003.Impact ofChi-chi earthquake onthe occurrence of landslides and deb-ris flows:example from the Chenyulan River watershed,Nantou,Tai wan.Engineering Geology,71(1-2):49-61.doi:10.1016/S0013-7952(03)00125-X
Mahdavifar,M.R.,Solaymani,S.,Jafari,M.K.,2006.Land-slides triggered by the Avaj,Iran earthquake of June22,2002.Engineering Geology,86(2-3):166-182.
Tang,C.,Zhu,J.,Li,W.L.,et al.,2009.Rainfall-triggereddebris flows following the Wenchuan earthquake.Bull.Eng.Geol.Environ.,68(2):187-194.doi:10.1007/s10064-009-0201-6
Yin,Y.P.,Wang,F.W.,Sun,P.,2009.Landslide hazardstriggered by the2008Wenchuan earthquake,Sichuan,China.Landslides,6(2):139-152.doi:10.1007/s10346-009-0148-5
Garca-Rodrguez,M.J.,Malpica,J.A.,Benito,B.,et al.,2008.Susceptibility assessment of earthquake-triggeredlandslides in El Salvador using logistic regression.Geo-morphology,95(3-4):172-191.doi:10.1016/j.geo-morph.2007.06.001
Huang,R.Q.,Li,W.L.,2009.Development and distributionof geohazards triggered by the“5.12”Wenchuanearthquake in China.Science in China(Ser.E),52(4):810-819.doi:10.1007/s11431-009-0117-1
Kamp,U.,Growley,B.J.,Khattak,G.A.,et al.,2008.GIS-based landslide susceptibility mapping for the2005Kashmir earthquake region.Geomorphology,101(4):631-642.doi:10.1016/j.geomorph.2008.03.003
Lin,C.W.,Liu,S.H.,Lee,S.Y.,et al.,2006.I mpacts ofthe Chi-chi earthquake on subsequent rainfall-inducedlandslides in central Tai wan.Engineering Geology,86(2-3):87-101.doi:10.1016/j.enggeo.2006.02.010
Lin,C.W.,Shieh,C.L.,Yuan,B.D.,et al.,2003.Impact ofChi-chi earthquake onthe occurrence of landslides and deb-ris flows:example from the Chenyulan River watershed,Nantou,Tai wan.Engineering Geology,71(1-2):49-61.doi:10.1016/S0013-7952(03)00125-X
Mahdavifar,M.R.,Solaymani,S.,Jafari,M.K.,2006.Land-slides triggered by the Avaj,Iran earthquake of June22,2002.Engineering Geology,86(2-3):166-182.
Tang,C.,Zhu,J.,Li,W.L.,et al.,2009.Rainfall-triggereddebris flows following the Wenchuan earthquake.Bull.Eng.Geol.Environ.,68(2):187-194.doi:10.1007/s10064-009-0201-6
Yin,Y.P.,Wang,F.W.,Sun,P.,2009.Landslide hazardstriggered by the2008Wenchuan earthquake,Sichuan,China.Landslides,6(2):139-152.doi:10.1007/s10346-009-0148-5
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