Mapping Urban Growth and Its Relation to Seismic Hazards in Istanbul

Abstract

In Istanbul, one of the most densely populated cities of Turkey, the population has grown rapidly over the last 30 years. In addition to being one of the rapidly flourishing cities in Europe, the city is positioned on the seismically active North Anatolian Fault (NAF). The form and rate of Istanbul’s fast urban growth has serious implications for seismic hazards. There have been some studies to map lateral urban growth for the city but they do not give satisfactory information about vertical urban growth and seismic hazards. We use DMSP night lights and Landsat data to map changes in land cover-land use in and around the city since 1984, and determine relations of these changes with the NAF. Changes in land use and intensity of development are identified by changes in night light brightness while changes in land cover are identified by changes in land surface reflectance. Aggregate changes in reflectance are represented as changes in subpixel mixtures of the most functionally and spectrally distinct spectral endmembers of land cover. Using standardized global endmembers, SVD composite images were produced for 1984, 2000 and 2011 and fraction change (δSVD) maps were produced for the decadal intervals. The results show that most of the urban expansion has occurred near the NAF. This has serious implications for seismic hazards in the future if the progression of large earthquakes continues to move westward toward the city.