鲁甸震区龙泉河次生山地灾害的分布规律与成灾模式

Distribution Regularity and Disaster Mode of Secondary Mountain Hazards Induced by the Ludian Earthquake in Longquan River Basin

以鲁甸灾区龙泉河流域的龙头山镇至天生桥段为研究对象,运用遥感解译和野外调查数据,探讨了研究区地震次生山地灾害的分布规律与成灾模式。结果表明:1地震次生灾害发育主要是由龙泉河右岸的次级小断裂与包谷垴—小河断裂的延伸部分(下水沟走滑断裂)共同作用引起的,龙泉河谷到断层的距离均小于2km,导致区内地震次生灾害发育密度最高达到4.125个/km;2次生灾害主要发生在凸形坡,占总数46.3%,凹形坡仅有24.1%,且在背向断裂方向的斜坡更容易发生地质灾害;3 60%的崩塌滑坡发育在浅表层的残坡积物中,40%岩质崩塌滑坡体中多为岩质较硬的灰岩、白云岩以及砾岩;4次生山地灾害主要以损毁道路、阻断交通,形成堰塞湖淹没上游、淤高下游河床、损毁上下游设施,造成建筑物损毁等模式呈现。

Taking Longtoushan-Tianshengqiao of Longquan river basin in Ludian as study area,using image interpretation and field investigation data,this paper discusses the distribution regularity and disaster mode of secondary mountain hazards reduced by Ludian earthquake.The results show that：（1）The secondary mountain hazards are mainly caused by the secondary faults at the Longquan river right bank and the extension of Baogunao-Xiaohe fault（Xiashuigou strike-slip faults）.The distance between Longquan river and the faults is smaller than two kilometers,which result in the 4.125/km maximum density of mountain hazards;（2）The mountain hazards mainly took place on the bulge slope,account for 46.3%,and furthermore,the hazards are more likely to take place on slopes of the back of faults;（3）60% of the collapses and landslides develop in the surface residual layer,and 40% of rocky landslide collapses are hard limestone,dolomite and breccias;（4）The secondary mountain hazards mode are as follows：damaging roads,interrupting traffic,forming barrier lakes which inundate upstream bed,damaging downstream bed and facility and buildings along the river.