Decorrelation of SAR data by urban damages caused by the 1995 Hyogoken-nanbu earthquake

Large part of urban area of around Kobe city were damaged by the 1995 Hyogo ken-nanbu earthquake. For detecting the damaged area, the authors computed correlation coefficients from single-look complex ERS-1/SAR data. Two types of correlations, intensity correlation and coherence were computed. Decorr elation was found in the damaged urban built-up area in the data pair of wh ich interval included the earthquake occurrence. The similarity of the deco rrelation between the intensity correlation and the coherence indicated tha t major factor of the decorrelation is closely related to interferometric p rocesses, which results in the change of speckle patterns in the single-loo k intensity images. A normalized difference was calculated from the correla tion coeffcients between the data pair including the earthquake occurrence and the pair before the earthquake. The distribution patterns of the pixels for which normalized difference was higher than a threshold showed good co rrespondence with the result of the ground survey. The result of this study indicates the possibility of detecting urban disasters using the decorrela tion of SAR data.