7 Selection of the Appropriate Methodology for Earthquake Safety Assessment of Dam Structures Hasan Tosun 1 and Evren Seyrek 2 1 Eskisehir Osmangazi University, Civil Engineering Department, Eskisehir 2 Dumlupinar University, Civil Engineering Department, Kutahya Turkey 1. Introduction Important lessons which reflect the seismic performance of dams under large earthquakes are available in the literature, (1971, San Fernando earthquake; 1985, Mexico earthquake; 1999, Kocaeli earthquake; 2001, Bhuj earthquake; 2008, Wenchuan earthquake). Seismic behavior of dams subjected to these severe earthquakes shows that earthquake safety of dams is an important phenomenon in dam engineering and requires a more comprehensive seismic studies. Dams built on the site with high seismicity have a high-risk potential for downstream life and property. Active faults near dam sites can cause to damaging deformation of the embankment. In general, strong ground shaking can result instability of the dam and strength loss of foundations. (Seed et al., 1969; Seed et al., 1975; Jansen, 1988; Castro et al.,1985). In the last decade, large earthquakes have killed many thousands of people and caused economic devastation, commonly as a result of building failures in seismic events. Therefore, meaningful seismic parameters are needed to perform a satisfactory evaluation of dam structure (Tosun, 2002). ICOLD (1989) stated that safety concerns for embankment dams subjected to earthquakes involve either the loss of stability due to a loss of strength of the embankment of foundation materials or excessive deformations such as slumping, settlement, cracking and planer or rotational slope failures. To obtain preliminary information about seismic parameters, the simplified procedures can be used. If the materials used in embankment are not susceptible to loss of strength and the hazard and risk ratings are low, the simplified analyses are entirely sufficient to define the seismic evaluation parameters. The safety concerns for concrete dams subjected to earthquakes involve evaluation of the overall stability of the structure, such as verifying its ability to resist induced lateral forces and moments and preventing excessive cracking of the concrete. For analyzing the loads, different procedures are performed. In the simplified analyses, peak ground motion parameters and response spectra are sufficient to define the seismic evaluation parameters. It is suggested the finite element method to be used for analyzing of most dams in high risk or hazard class.