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MCEER Earthquake Reconnaissance Investigation

Preliminary Regional Damage Assessment

Figure 4 shows the extent of ‘Quickbird’ satellite coverage of Bam, acquired by the University of California at Irvine (UCI), and the Earthquake Engineering Research Institute (EERI) as part of their Learning from Earthquakes Program. The first image is dated September 30th 2003 – approximately 3 months before the earthquake struck. Visual comparison with the second image, taken just over one week after the earthquake on 3rd January 2004, reveals widespread changes. Many of the differences are caused by building collapse, although seasonal variations in vegetation may also be present.

 

Satellite image of Bam, Iran taken in Sept. 2003 before the earthquake.
Satellite Image of Bam, Iran taken in January, 2004, after the earthquake

(a)

(b)

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Figure 4 Pan-sharpened QuickBird satellite coverage of Bam, acquired: (a) in September 2003 ‘before’ the earthquake; and (b) in January 2004 ‘after’ the earthquake. In addition to differences between the scenes due to urban damage, the greenness of vegetation has changed because of seasonal effects and sensor look angle variation. Imagery courtesy of DigitalGlobe, http://www.digitalglobe.com.

 

These changes were quantified using a texture-based change detection algorithm originally developed for the 2003 Algerian earthquake. In the resulting building damage map (Figure 5), red and orange areas are associated with extreme changes where structures have collapsed. These zones are concentrated within eastern districts of Bam, a distribution which corresponds closely with preliminary results of a ground-based damage assessment (National Cartographic Center of Iran, 2004).

 

VIEWS damage assessment image showing many orange and yellow blocks throughout the image with green blocks concentrated towards the center

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Figure 5 Preliminary VIEWS damage assessment for Bam, obtained using texture-based change detection. Red and orange areas correspond with pronounced changes between the ‘before’ and ‘after’ scenes, which are primarily associated with collapsed buildings. To aid visualization, results are overlaid with QuickBird coverage from 30th September 2003. Imagery courtesy of DigitalGlobe, http://www.digitalglobe.com.

 

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