玉树地震滑坡影响因子敏感性分析

 2010年玉树地震触发了2036处滑坡,总面积为1.194km²。采用滑坡面积百分比(LAP)与滑坡点密度(LND)两个指标对地震滑坡影响因子进行敏感性分析,这些因子包括地震因子(震中、宏观震中、地表破裂、地震动峰值加速度、同震位移),地形因子(高程、坡度、坡向、曲率、坡位、水系),地质因子(岩性、断裂),其他因子(公路、归一化植被指数)。结果表明,(1) 距地表破裂越近,滑坡越易发生;除个别分级异常外,距宏观震中越近、同震位移越大,滑坡越易发生;滑坡易发程度与震中、PGA的关系不显著。(2) 坡度越大,滑坡易发程度越高;滑坡的易发高程区间为<4km;易发坡向为北东、东、南东;除平坡外,坡位越低,滑坡越容易发生;距离水系越近,滑坡越易发生;曲率与滑坡对应关系表现出坡面凸凹不平的容易发生滑坡,坡面光滑的不容易发生滑坡。(3) 易发地层是Q₄^al-pl (湖沼淤泥和泥炭沉积)、N(石英细砂岩,底部为角砾岩)、T₃kn¹(灰色长石砂岩、长石石英砂岩夹粉砂岩、板岩、灰岩);滑坡发生与断裂的关系不明显。(4) 越靠近公路,滑坡越容易发生;植被覆盖越少,滑坡越易发生。

Susceptibility Analysis of Impact Factors of Landslides Triggered by Yushu Earthquake

2036 landslides were triggered by the 2010 Yushu earthquake, in a total area of 1.194km². The Landslide Area Percent (LAP) and the Landslide Number Density (LND) are selected as two indices for the susceptibility analysis of landslide impact factors. The impact factors of landslides include the earthquake impact factors such as the epicenter, the macro-epicenter, the main co-seismic surface fault-rupture, the Peak Ground Acceleration (PGA), and the co-seismic displacement; the topography impact factors such as the elevation, the slope angle, the slope aspect, the slope curvature, the slope position, and the drainages; the geology impact factors such as the lithology and the faults; and other impact factors such as the roads and the Normalized Difference Vegetation Index(NDVI). The results show that: (1) Both LAP and LND have strong positive correlations with the distance from the main co-seismic surface fault-rupture, and also have positive correlations with the macro-epicenter and co-seismic displacement except for individual classifications, but the correlations between the landslide occurrences and the epicenter, and PGA are not clear-cut. (2) The greater the slope angle, the higher the probability of landslide occurrence; the elevation less than 4000m sees a high susceptibility to landslide occurrences; it can be found that the slopes facing NE, E, and SE see relatively higher LAP and LND values than other directions; the higher the slope position, the higher the landslide susceptibility except for flat slope; landslides have positive correlations with the distance from drainages; rough slopes are more prone to landslide occurrence than smooth slopes. (3) The stratums of Q₄^al-pl (Alluvium, fluvial deposits, gravel), N (Quartz sandstone, breccia), and T₃kn¹ (Feldspathic sandstone, siltstone, slate, limestone, phyllite) see concentrated landslide activities, the correlation between the landslide occurrences and the faults is not clear-cut. (4) The closer to roads and the more sparse of the vegetation, the more susceptibility to landslide occurrences.