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选取位于白龙江地质灾害最严重的中游区域,且受人类影响较弱的典型泥石流沟构林坪为例,基于SBAS InSAR技术监测分析2008年“5.12”汶川特大地震前后该流域的地表形变特征.研究发现横穿该流域上下游分界处的迭部-白龙江断裂自2008年前以8.0 mm/a的相对速率稳定抬升,在震后迅速增至11.5 mm/a.根据资源卫星、Geoeye,SPOT影像调查资料,与InSAR结果相应,该流域地质灾害的增幅明显上升.地震对地质灾害的作用表现为直接激发作用和潜伏后发作用,在白龙江流域,汶川地震不仅直接引发大量次生地质灾害,还使该流域的岩土结构、强度等遭到破坏,孕育大量潜在灾害,使该地区地质灾害长期并将会频繁发生,次生灾害的分布具有“上盘效应”和沿断裂带集中分布的特点.
Taking the typical debris flow gully ridge located in the middle reaches where Bailongjiang is the most serious geological hazard, taking the SBAS InSAR technique as an example, the surface deformation characteristics of the basin before and after the “5.12 ” Wenchuan earthquake are analyzed The study found that the Bailongjiang fault, which crosses the upper and lower boundary of the basin, rose steadily at a relative rate of 8.0 mm / a from 2008 to 11.5 mm / a after the earthquake, according to the resource satellite Geoeye SPOT According to the results of the image survey and the InSAR results, the increase of geological disasters in this drainage basin obviously increases.The direct seismic action and latent late-onset effect of earthquakes on geological disasters show that the Wenchuan earthquake not only directly triggered a large number of secondary geological disasters in the Bailongjiang River basin, It also destroyed the geotechnical structure and strength of the river basin and created a large number of potential disasters so that the geological disasters in the area will occur frequently and frequently. The distribution of secondary disasters is characterized by “hanging-plate effect” and concentration along the fault zone Distribution characteristics.