汶川地震触发崩滑地质灾害空间分布及影响因素

通过遥感解译和实地考察,获取了2008年汶川地震触发崩滑的空间分布,利用GIS空间分析和Lo-gistic回归,分析崩滑的空间分布特征及其影响因素,建立了地震触发崩滑与其影响因素之间的回归方程。结果表明,(1)研究区共有5 154个崩滑群,覆盖总面积1 139 km2;(2)崩滑沿北川—映秀发震断层的两侧(断层上盘区占90%),呈北东向宽度不一的条带状分布;(3)Ⅺ和Ⅹ烈度区崩滑面积占区域面积的73.2%,Ⅷ度及以下烈度区崩滑面积比例较小;(4)崩滑发育及空间分布不仅受控于发震断层的活动,断层上下盘效应、地形放大效应等也是其重要影响因素。崩滑与其影响因子的回归方程表明:(1)到北川—映秀发震断层距离因子和到震中距离因子的偏回归系数远大于其他因子的偏回归系数,北川—映秀断层发震活动是控制崩滑空间分布的主导因子;(2)岩性软硬程度对崩滑空间分布的影响不显著;(3)地形坡度、高程、坡度变率、多年累积降雨、人工修路及植被覆盖对崩滑的发育产生影响。地形高程因子对崩滑空间分布的影响大于坡度、坡度变率因子的影响。人工道路、多年降雨及植被覆盖对地震崩滑的影响程度依次降低。

The distribution of landslide triggered by Wenchuan earthquake and its causative factors

Landslide triggered by Wenchuan earthquake was interpreted based on multi-source remote sensing data.A logistic regression model was built between the landslide distribution and the control factors of the landslide.The number of landslide area interpreted was 5145,which covered a total area of 1139 km2.By using spatial analysis technology,it is found that(1) there are two types of distribution patterns existing in the landslide,one is a linear distribution along seismogenic fault and another is cluster-like around epicenter of Wenchuan earthquake;that(2) in the Ⅹ and Ⅺ degree seismic intensity zones,there are 73.2% landslide area and in the other region with Ⅷ degree or Less seismic intensity,there are few landslides;that(3) the distribution of landslide was not only controlled by seismogenic fault rupture,but also affected by the topographic amplification and fault's upper and lower plate;there is 90% landslide area located in the upper plate of seismogenic fault.Furthermore,the logistic regression model indicated that(1) the seismogenic fault was the dominant factors controlling landslide distribution and the model's partial regression coefficient of the factor of distance to Beichuan-Yingxiu fault was larger than that of any other factors in the logistic regression model;that(2) the factors of rock hardness are not significant,which indicated that rock hardness did not affect the distribution of landslide triggered by earthquake in our study area;that(3) in our model,the factors of elevation,terrain slope,slope change rate,the accumulated rainfall,human activity and the vegetation coverage all affect the landslide spatial distribution.