Page - 921 - in Book of Full Papers - Symposium Hydro Engineering

segment. Mean PGA + 50% and Mean PGA + 84% are mean peak ground acceleration at the 50th percentile and Mean Peak Ground Acceleration at the 84th percentile, respectively. A detailed study was performed to identify all possible seismic sources for the seismic hazard analyses of the dam sites, as based on the macro seismo- tectonic model of Turkey. The National Disaster Organization and other Institutes prepared the map for general use. But it was modified by the author and his co- workers to use for dam projects at the Earthquake Research Center in Osmangazi University. Local geological features and seismic history were also taken into account to quantify the rate of seismic activity in dam sites. As a result of detailed evaluation, total area covering all basins was separated into four seismic zones. These seismic zones and historical earthquakes are given in Fig. 1. These zones including faults and earthquakes occurred in the basin along last 100 years. The number of earthquakes having a magnitude on the basis of surface wave (Ms), which is greater than 4.0, is 1455. The numbers of earthquakes with Ms that are greater than 6.0 are 34 for dam sites.There is no earthquake having a magnitude greater than 7.0 in the basin. Fig. 1. Energy sources and earthquakes in west Anatolia region of Turkey. The deterministic analyses indicate that peak ground acceleration (PGA) changes within a wide range. The PGA values ranges from 0.116g to 0.442g for the mean Peak Ground Acceleration at the 50th percentile and from 0.189g to 0.702g for the mean Peak Ground Acceleration at the 84th percentile given in table 2. According to the updated DSI guidelines, the PGA values at the 84th percentile should be taken into account for five dams analyzed throughout the study, when considered deterministic approach (DSI, 2012). For only Alacati Kutlu Aktas dam, the PGA values at the 84th percentile shoud be considered Table 3 shows the summary of DSI seismic guidelines for dynamic analyses. 921