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本文利用格网技术(Fishnet),对龙门山地区“5.12”大地震震后的多期次遥感影像数据及基础地理信息数据进行评价、整合并实现了动态管理,在此基础上得到覆盖整个龙门山构造带的、能够反映不同地物信息的影像群。汶川地震造成了大量山体崩塌、滑坡、泥石流等地震场地灾害,这些灾害体表现为成群、成带分布的特征,并且单一的小灾害体分布面积较小,但总体规模较大,难以从影像上准确无误提取所有单一的灾害体等特点。鉴于上述原因,本文提出以灾害体分布密度,将地震场地灾害分成6个密度等级,并结合格网(Fishnet),通过不同时相、不同数据源的影像之间的对比分析,解决了高起伏度地区影像中阴影区的场地灾害的提取等问题,完成了汶川地震场地灾害监测分析及野外验证,最终得到汶川地震场地灾害分布面积为972.081km2。汶川地震场地灾害的分布平行和垂直于龙门山断裂带均表现出明显的分段和分带特征。平行于龙门山断裂带,地震场地灾害的分布表现出明显的分段特征:西南部灾害体呈连片集中分布,影响范围较宽;中部表现为细脖子化,影响范围较窄;到东北部灾害体表现为以小规模的灾害体散点状分布,但是影响的区域较广。垂直龙门山断裂带方向,地震场地灾害的分布表现为分带特征:汶川地震场地灾害约80%分布在中山带;后山带,地震场地灾害主要沿着汶川-茂汶断裂及部分河流两侧分布于汶川境内;而在前山带,地震场地灾害一部分在绵竹市和安县境内的北部呈现密集分布,另一部分在江油市辖区内多呈散点状分布。
This paper evaluates the multi-temporal remote sensing image data and basic geographic information data after the earthquake of “5.12” in the Longmenshan area by using Fishnet technology, integrates and realizes the dynamic management, and on this basis, obtains the coverage Longmen Shan tectonic belt, the image group can reflect the different features information. The Wenchuan earthquake caused a large number of earthquakes in landslides, landslides and mudslides. These disasters showed the characteristics of flocks and belts, and the distribution of single small calamities was small but of a large scale. Accurately extract all single disaster and other characteristics. In view of the above-mentioned reasons, this paper proposes to divide the disasters in seismic sites into six density classes according to the distribution density of disasters, and with Fishnet, through the contrast analysis between the images of different time phases and different data sources, Degree of regional images in the shadow area of the site disaster extraction and other issues, completed the Wenchuan earthquake site monitoring and field verification and field verification, the final Wenchuan earthquake disaster distribution area of 972.081km2. Wenchuan earthquake site distribution parallel and perpendicular to the Longmenshan fault zone showed obvious segmentation and zoning characteristics. Parallel to the Longmenshan fault zone, the distribution of disasters in seismic sites shows obvious characteristics of segments: the contiguous distribution of disasters in the southwestern part has a wide range of impacts; the central part shows a thin neck with a narrow impact range; and to the northeast Disaster bodies are scattered in small-scale disasters, but the impact is broader. In the direction of vertical Longmenshan fault zone, the distribution of the disasters in the earthquake field is zonation: about 80% of the Wenchuan earthquake site distribu- tion is located in the Zhongshan zone; and the back-mountain belt and the earthquakes are mainly along the Wenchuan-Maumian fault and on both sides of some rivers Distributed in Wenchuan territory; while in the former mountain belt, some of the earthquake site disasters were densely distributed in the northern part of Heian County in Mianzhu City and the other part was distributed in a scattered manner in the area of Jiangyou.