摘要
针对汶川5.12大地震,对由地震引起的地质次生灾害发生的坡度和坡向进行了统计,分析了地表破坏的易发坡度、坡向及其与震中的关系等。另外,分别以不同震中距为缓冲区、以平行中央断裂带的各级缓冲区、以等烈度区为缓冲区对地震引起的地表破坏的空间分布以及发生地表破坏的坡度在各级缓冲区中的变化进行了分析。结果表明:①地震引发的滑坡及滑坡群共5093个,总面积大约958km2;②在30°～44°坡度区间地表破坏发生的数量最大,42°坡度为地表破坏发生概率的拐点。主要的地表破坏发生在迎着地震波传播的坡向上;③随着震中距的增加,地表破坏的发生概率逐渐减小,震中距40km以内的速度减小非常迅速,40km以外则整体上缓慢减少,局部略有起伏。各缓冲区中发生地表破坏的平均坡度比缓冲区内的地形平均坡度大4°左右。④地震引发的地表破坏主要受到断裂带的控制,有64.17%的地表破坏发生在中央断裂带两侧10km范围内。⑤高地震烈度区域引发的地表破坏率远远大于低烈度区域,在烈度为Ⅺ度的区域内发生地表破坏率达到14.5%,而Ⅶ度烈度带上引发地表破坏率仅为0.01%。
The devastating Ms8.0 earthquake struck Wenchuan,China on 12 May 2008. It caused considerable damage and lots of secondary geological hazards such as landslides,collapses,mud-rock flows etc. Based on the interpretation of remote sensing images,this study built the geological hazards database. The areas in different slopes and aspects vulnerable by geological hazards were calculated using GIS tools,and the relationship between the ground damage induced by 5.12 Wenchuan earthquake and slopes was also analyzed. In addition,three kinds of buffer analysis methods were employed in this paper in order to identify the spatial distribution patterns of the ground damage. The results shows that：① the number of the secondary geological hazards interpreted by RS images in the study area was more than 5093 and the total area of ground damage induced by the Wenchuan earthquake was more than 958 sq. km. ② Most of the ground destruction occurred in the slope gradient ranging from 30° to 44°. Geological hazards distribution also shows a correlation with the orientation of mountain slopes,the geological hazards mainly happened at the aspects that faced the seismic wave. ③ With the increasing of epicenter distance,the probability of occurrence of geological hazards decreased gradually. The percentage of geological hazards within the 40km epicenter distance deceased greatly,and the average slope of geological hazards in every buffer was about 4 larger than the average slope of the buffer they located. ④ The geological hazards were distributed mainly around the seismic faults,and about 64.17% of them was distributed within the 10km range around the main seismic fault zone. ⑤ The geological hazards happened most frequently in the regions with high seismic intensity than in regions with low seismic intensity. The percentage of geological hazard was happened in region with Ⅺ degree of intensity was about 14.5% while it was only about 0.01% in region with Ⅶ degree of intensity.
出处
《地质学报》
EI
CAS
CSCD
北大核心
2010年第9期1283-1291,共9页
Acta Geologica Sinica
基金
国家自然科学基金重点项目(编号4083-0529)资助的成果
关键词
地震
汶川
次生地质灾害
缓冲区
空间分析
earthquake
Wenchuan
secondary geological disaster
buffer
spatial analysis
