Analysis of seismogenic damage in Bam, Iran, using Envisat ASAR data

Significant surface changes occur frequently as a result of natural hazard events, of which earthquakes are considered the deadliest and most destructive, affecting mainly man-made structures. The detection, mapping and assessment of earthquake-related urban damage are critical, particularly in remote or inaccessible areas. Spaceborne satellite data are obtained without the necessity of accessing a location, covering large areas. Especially spaceborne SAR’s weather-and-sunlight independence makes it a potential tool for post-disaster structural damage assessment of urban areas.
In this research we use a series of Envisat ASAR images to assess the capacity of InSAR data for detecting urban damages caused by the occurrence a 6.6 magnitude earthquake in Bam, Iran, on December 26, 2003. We analyze InSAR properties, such as complex coherence and signal amplitude and their sensitivity to changes in ground surface and urban damage, both induced by an earthquake event. These changes, among other causes, lead to quantifiable decorrelation of InSAR data.
A number of methods for post-earthquake urban damage assessment using spaceborne SAR images have been proposed by several authors. Of these methods, pixel by pixel comparison and change detection of InSAR properties are reviewed and analyzed in this study to compare and evaluate both their actual potentials and limitations through validation. This is done through correlating available damage maps created after the earthquake by competent entities. From this analysis, we calculate and map InSAR properties and quantitatively isolate earthquake-related urban damage from other sources of decorrelation.