Seismic Microzonation of Erbaa, Tokat Province, Turkey, Based on Analytical Hierarchical Process

Abstract

This study is to develop a seismic microzonation map using Analytical Hierarchical Process (AHP), one of the Multicriteria Decision Analysis methods based on Geographical Information Systems. The study area, Erbaa, is located along the eastern segment of the North Anatolian Fault Zone and is one of the largest towns and one of 12 districts within Tokat Province (population, similar to 176,000) in the Middle Black Sea Region of Turkey. Erbaa is located on the southwest bank of the Kelkit River. After the disastrous 1942 (M-s = 7.2) and 1943 (M-s = 7.6) earthquakes, the settlement was shifted southward. Erbaa is one of the most rapidly growing metropolitan areas of this province, with a population of similar to 96,000 people. Therefore, a microzonation study is needed for new settlement places. The data are classified as fundamental input data and derived input data, which are both considered in the AHP method. Fundamental input data include topographical, slope, aspect, lithology, and depth to groundwater table maps. The derived input data involve distance to fault, site classification based on shear wave velocity for the upper 30-m depth, amplification, and liquefaction-induced ground deformation maps, representing the seismic-based layers, produced from various analyses. Weight and rank values are assigned to different layers and to the corresponding classes of each layer. The resulting microzonation map reveals that the northern part requires detailed geotechnical investigation and that the southern part of the area is much more suitable for settlement.