Post-earthquake building collapse: a comparison of government statistics and estimates derived from SPOT HRVIR data

On 17 August 1999 at 3:02 a.m. local time the Izmit earthquake occurred on the North Anatolian Fault Zone (NAFZ) in north-west Turkey. This earthquake caused considerable damage in the urban areas of Izmit, Adapazari (Sakarya), Golcuk and Yalova. This study used three different data sources to estimate the proportion of Adapazari that contained collapsed buildings: (i) government statistics on the number of collapsed buildings; (ii) the difference between pre- and post-earthquake land cover estimated from classified SPOT HRVIR XI images; and (iii) land cover estimated from density-sliced SPOT HRVIR Panchromatic image recorded after the earthquake. The results were similar at 16%, 16.1% and 15.5%, respectively. These were all slight overestimates; however, the remotely sensed estimates provided the spatial context of building collapse and in doing so highlighted areas of previously uncontrolled building.