2013年芦山地震滑坡空间分布分析——以太平镇东北方向的一个典型矩形区为例

SPATIAL ANALYSIS OF LANDSLIDES TRIGGERED BY THE 2013 M_S 7. 0 LUSHAN EARTHQUAKE: A CASE STUDY OF A TYPICAL RECTANGLE AREA IN THE NORTHEAST OF TAIPING TOWN

选择2013年芦山地震中受到强烈地震动的太平镇东北方向一个20km×10km的矩形区作为研究区,开展芦山地震滑坡空间分析工作。基于震后野外调查与高分辨率航片人工目视解译法,建立了研究区内地震滑坡空间分布图。结果表明,在研究区内芦山地震至少触发了688处滑坡,区域内滑坡点密度为3.44个/km2。统计了地震滑坡密度与地形因子、地层岩性、地震因子的关系。滑坡最易发高程为1600～1800m;滑坡密度大体随着坡度的增加而增加;E与SE方向是地震滑坡的易发坡向与高发坡向;凸坡的地震滑坡易发性最高。二叠系阳新组(Py)的灰岩与白云岩、元古界花岗岩(Pt)是地震滑坡的易发岩性。地震因子与滑坡密度的统计结果表明,大体上PGA值越大,地震烈度越高,地震滑坡越易发生;地震滑坡与距离双石-大川断裂的统计结果表明在双石-大川断裂的出露处地震滑坡密度未发生突变。因子的交互统计结果表明了坡度与PGA这2个因子作用于地震滑坡的独立性。

In this paper,a rectangle area of 20km× 10km at the northeast of Taiping Town, which suffered strong shaking during the April 20,2013 Ms 7.0 Lushan earthquake, was selected as the study area for spatial analyses of landslides triggered by the earthquake. Landslide distribution map of the study area was prepared based on quick field investigations and visual interpretation of high-resolutions aerial photographs. It is showed that at least 688 landslides were triggered by the Lushan earthquake and the landslide number density （LND） of the study area is 3.44 landslides/km2. Correlations of landslide number density with topographic, geologic and seismic parameters were analyzed based on the landslide inventory. The results show that the steeper the slopes, the greater the landslide number density values; the highest LND value appears at ranges from 1 600m to 1 800m in elevation. The landslides have preferred orientations,dominated by the east and SE directions. LND values of convex slopes are relatively higher. The limestone and dolomite of the Yangxin Group, Permian （Py） and granitic rocks of Proterozoic （Pt）experienced more concentrated landslides. In general,the higher the PGA value and seismic intensity zone, the greater the LND value. Correlation of landslide number density with distance from the Shuangshi-Dachuan Fault shows that there was not sudden change of LND value near the fault. The factor interaction statistics show that the slope angle and PGA affect the occurrence of earthquake-triggered landslides independently.