汶川地震灾区滑坡风险区划研究

地震滑坡是在地震瞬间诱发的滑坡灾害。本文讨论了汶川地震灾区滑坡风险区划与常规滑坡风险区划的区别,认为地震滑坡风险区划应该在危险度区划中增加与地震相关的指标因子,如滑坡震中距和滑坡断层距。从而反映地震动能量对地震滑坡发育的贡献作用。而易损度区划中是难以体现地震因素作用的,这里采用滑坡密度、人口密度、道路密度、建筑物密度、耕地密度这5个指标进行易损度评价。最后采用权重叠加法进行了汶川地震极震区10个县市(面积26175.77km2)的滑坡风险区划,其中高、较高风险区分别占全区面积的9.03%和14.61%。说明震后灾区依然存在一定的滑坡风险。汶川地震极震区中,北川、青川、都江堰、彭州4地应该成为滑坡风险防御的主要地区。对滑坡风险区划结果进行了实地抽样检验,证明区划结果基本符合汶川极震灾区的情况。由此可见,本文介绍的地震滑坡风险区划方法是可靠的。

STUDY ON WENCHUAN EARTHQUAKE-INDUCED LANDSLIDE RISK ZONATION

Landslides that are occurred during the earthquake are called seismic-landslides. This paper discusses the difference between the earthquake-induced landslide risk zonation and the general landslide risk zonation. It considers that some factors related to earthquake should be taken into the consideration in earthquake-induced landslide risk zonation. They include the distance between the landslide location and epicenter and the fault's buffer distance. They can reflect the role of earthquake dynamic energy to landslide formation. However, it is hard to reflect the earthquake effect in the vulnerability assessment. Five factors including landslide density, population density, road density, building density, and cultivated land density are adopted to evaluate the study area vulnerability. Finally, the contributing weight model is adopted to evaluate the landslide risk. The result shows that the higher and the high risk region are accounting for 9.03% and 14.61% of the whole study area respectively. This demonstrates that the disaster area after the Wenchuan Earthquake is still facing the landslide hazard threats. In the meizoseismal area, the counties of Beichuan, Qiangchuan, Dujiangyan, and Pengzhou should be regarded as the main landslide risk prevention areas. After field sampling and validation, the results are proved to be consistent with the actual Wenchuan earthquake regions. Thus, the method in this paper is reliable.