Estimation of Earthquake Damage Through Radar Interferometry (Case study: Bam 2003 Earthquake)

The estimate of the damage caused by the earthquake and other natural disasters in the first days after the occurrence of these events can provide a quick damages assessment and help to manage the crisis. Several methods are available to investigate the extent of earthquake’s damage. Optical remote sensing, photogrammetric methods (UAVs and LIDARs), radar interferometry (InSAR) and field observations are examples of the operational methods. Today, InSAR technology has become a powerful yet inexpensive tool for monitoring deformation and changes in the Earth's crust. The Coherence Product is derived from SAR imagery. The lack of coherence in radar images can be due to several factors such as vegetation, changes in the dielectric coefficient in the master and slave images, high gradient slop areas, soil erosion, damage degradation and etc. In this paper, we have tried to estimate the extent of the damaged area by focusing on InSAR technique and eliminating cells that have lost their coherence due to vegetation, dielectric coefficients, and high mountain range areas. In this regard, Envisat Advanced SAR images of Bam, Iran, that were acquired before and after the 2003 earthquake were used. The coherence of cells with a mean value of 0.2 in the area of Arg-e-​Bam with its high degradation level indicates the ability to use this criterion in the rate of destruction. The results of the Bam earthquake investigation indicate that about 23.5% of 14290 hectares of the study area collapsed and about 31% of it had high degradation.