SPOT HRV data analysis for detecting earthquake-induced changes in Izmit, Turkey

SPOT HRV (XS and PAN) images acquired on 17 July 1999 and 20 August 1999 were used to detect earthquake-induced changes on 17 August 1999 in Izmit, Turkey. The pre-event and post-event images were geometrically and radiometrically calibrated to each other. In order to preserve the spatial and spectral information of the two data-sets the multispectral and panchromatic images were merged. The change areas were detected by subtracting the image brightness values for the near-infrared channel (Band 3) of the merged July image from that of the August image. The overall accuracy of the change image was found to be 83%. Upon finding the change areas, the emphasis was placed on the detection of the damaged building blocks within a selected urban area in the change image using automated analysis techniques. Our results show that the difference image of the merged pre- and post-event SPOT HRV data can successfully reveal the location of the earthquake induced changes. The procedure also demonstrates that the building blocks that contain collapsed buildings can be detected and categorized according to pre-defined damage conditions through the analysis of the merged SPOT HRV data.