Effects of basin edge on the distribution of damage in 1995 Dinar, Turkey earthquake

An earthquake of magnitude M_L=5.9 occurred in Dinar, a town located at the edge of an alluvial basin in Southeast Anatolia, Turkey. Inflicted structural damage throughout the town was highly concentrated in a region located on the alluvium and adjacent to the rock outcrop bounding the eastern side of the town. As an attempt to explain this discrepancy, possible effects of the edge of basin on which the town is located were investigated through 1D and 2D response analyses. Response spectra, computed at distinct locations of the town were contrasted to the building damage statistics of the three zones identified in the town. It is found that the 1D analyses considerably underpredict the spectral response in the heavily damaged area. Differences between the spectral responses obtained from the two approaches diminish with increasing distance from the rock outcrop. These results, which indicate that the 2D amplification was significant over a distance from the edge of the basin, provide a meaningful explanation for the observed distribution of damage throughout the town.