Abstract: On August 3, 2014, an M_W6.5 earthquake occurred in Ludian County, Yunnan Province, which triggered significant landslides and caused serious ground damages and casualties. Compared with the existing events of earthquake-triggered landslides, the spatial distribution of co-seismic landslides during the Ludian earthquake showed a special pattern. The relationship between the co-seismic landslides and the epicenter or the known faults is not obvious, and the maximum landslide density doesn't appear in the area near the epicenter. Peak ground acceleration (PGA), which usually is used to judge the limit boundary of co-seismic landslide distribution, cannot explain this distribution pattern. Instead of correlating geological and topographic factors with the co-seismic landslide distribution pattern, this study focuses on analyzing the influence of seismic landslide susceptibility on the co-seismic distribution. Seismic landslide susceptibility comes from a calculation of critical acceleration values using a simplified Newmark block model analysis and represents slope stability under seismic loading. Both DEM (SRTM 90m)and geological map (1 ︰ 200^￣￣000)are used as inputs to calculate critical acceleration values. Results show that the most susceptible slopes with the smallest critical accelerations are generally concentrated along the banks of rivers. The stable slopes, which have the larger critical accelerations and are comparably stable, are in the places adjacent to the epicenter. Comparison of the distribution of slope stability and the real landslides triggered by the 2014 M_W6.1 Ludian earthquake shows a good spatial correlation, meaning seismic landslide susceptibility controls the co-seismic landslide distributions to a certain degree. Moreover, our study provides a plausible explanation on the special distribution pattern of Ludian earthquake triggered landslides. Also the paper discusses the advantages of using the seismic landslide susceptibility as a basic map, which will offer an additional tool that can be used to assist in post-disaster response activities as well as seismic landslides hazards zonation.

Key words: earthquake-triggered landslide, Newmark model, seismic landslide susceptibility, the Ludian earthquake

摘要： 2014年8月3日发生于云南省东北部鲁甸县的M_S6.5地震触发了显著的同震滑坡并造成了严重地面破坏和人员伤亡。与已有地震诱发滑坡事件相比，鲁甸地震同震滑坡的空间分布较为特殊：与震中和已知断裂的关系都不明显，滑坡密度最大的区域并不在震中附近区域，且通常用于判断滑坡空间分布范围的地震动峰值加速度（PGA）也不能解释这样的分布格局。与以往研究地震滑坡与地质构造、地形地貌等影响因素相互间的关系不同，文中着重讨论地震滑坡敏感性对地震滑坡的控制作用。基于Newmark刚体滑块模型，文中计算了鲁甸地震滑坡影响区的坡体临界加速度值，并用来衡量地震滑坡敏感性程度：临界加速度值小，表明地震滑坡敏感性程度高，滑坡需要的外力较小，坡体在地震动作用下容易失稳；反之，坡体就越稳定。结果表明，鲁甸震区地震滑坡敏感性程度较高的地区主要沿牛栏江及其支流沙坝河、龙泉河两岸分布，震中及其北部地区的地震滑坡敏感性程度较低。对比研究区坡体地震滑坡敏感性分布与实际滑坡分布，可以看出二者之间具有较高的一致性：地震滑坡敏感性程度较高的区域往往是发生大量滑坡的地区。进一步，文中讨论了根据地震滑坡敏感性判断同震滑坡格局的优势，认为地震滑坡敏感性对同震滑坡的分布起到了控制作用；同时，区域性地震滑坡敏感性的研究不仅有助于理解同震滑坡分布格局，还可以为震源构造的研究提供依据，并且可以作为震后滑坡快速评估及地震滑坡危险性区划的基础。

关键词: 地震滑坡, Newmark刚体滑块模型, 地震滑坡敏感性, 鲁甸地震