Earth Observation for Earthquake Disaster Monitoring and Assessment

Abstract

China is a country where earthquakes and many other disasters happen often. After earthquakes, roads are damaged, traffic is blocked off, secondary disasters occur frequently, weather conditions become adverse, and communications are interrupted, which makes it difficult to gather data from stricken regions. And the big problem for recovery operations is that there is no accurate information about the situation. Earth observation technology, which has many advantages including high-speeds, maneuverability, and macroto microlevel observation, has shown its importance for gathering information about stricken regions and making reasonable recovery decisions. Optical Earth observation technology can provide vivid images for target interpretation and disaster information extraction. Maneuverable, flexibile airborne optical observation technology can especially provide real-time surface images, which also obtains information about collapsed houses, broken roads, geological disasters, barrier lakes and so on. It plays an important part in disaster mitigation activities (Guo et al., 2010a). Synthetic aperture radar (SAR) not only has the capability of all-weather monitoring, but also is sensitive to geometric shape and movement, which becomes an efficient tool to analyze and evaluate recent earthquakes (Guo et al., 2000; Guo et al., 2010b). Multi-mode SAR data can provide many kinds of information for disaster research. Wide-mode SAR images and In-SAR images are important methods for detecting terrain deformation. Wide-mode SAR images can analyze the faulted zone and lithologic characteristics in stricken regions from a macrolevel,because it acquires large-scale image (Guo et al., 2000). In-SAR images yield information about surface deformation size and spatial distribution acquired from twoscene repeat-pass data (Massonnet & Feigl, 1998). Polarimetric SAR images, due to the sensitivity to target structures, can be used to extract the distribution of collapsed buildings. After the Wenchuan and Yushu earthquakes, some departments took full advantage of airborne and satellite remote sensing technology, or unmanned aerial vehicles, to obtain images of the disaster area, which played a very important role in disaster emergency monitoring and disaster assessment and reconstruction (Guo et al., 2010ab; Singh et al., 2010; Liou et al., 2010). Besides monitoring targets directly affected by the disaster, such as collapsed buildings (Lei 2009), remote sensing can observe secondary damage such as barrier lakes, collapse, landslide, debris flow et al. (Cui et al, 2008; Wang et al, 2008; Liu et al., 2009; Huang et al., 2009; Ge et al., 2009; Xu et al., 2009; Han et al., 2009; Zhuang et al., 2010; Zhang et al., 2010; Xu et al., 2010).