关键词: 芦山地震, 崩塌滑坡, 滑动方向, 宏观震中, 发震断层

Abstract: Geological disaster distribution induced by the 2013 M_S7.0 Lushan earthquake shows clear hanging wall effect and direction effect under reverse fault motion. No surface rupture was found in the post-earthquake emergency field surveys. We developed a detailed geo-spatial database of 2230 rock falls and landslides based on post-earthquake field surveys and examination of high-resolution aerial photographs across the disaster area. Landslides triggered by earthquake, dense aftershocks and isoseismal map provide clues to study the unrevealed causative fault.Statistics show that rock falls and landslides have a dominant slide direction of southeast(135°～144°), which is perpendicular to the strike of the causative fault. This result is consistent with the focal mechanisms. From distribution and density of seismic disasters, the macroscopic epicenter was relocated on the northern edge of Baosheng Town, ～3.6 km from the instrumental location. The probable surface rupture may appear on the edge of dense region of coseismic landslides and aftershocks, paralleling to the Shuangshi-Dachuan Fault. Because of difference in weatherability of rocks, linear cliffs or high-angle topography are formed between different strata or igneous rocks, and these regions are susceptible to rock falls and landslides under the action of strong earthquake.

Key words: Lushan earthquake, rock falls and landslides, slide direction, macroscopic epicenter, causative fault