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5. CONCLUSION The seismic hazard at the Gambiri diversion dam site has been estimated by means of probabilistic and Deterministic methods to obtain the ground motion levels for the design of the dam and appurtenant structures. The dams and relevant structures are designed for the median (84th percentile) of the maximum credible level (MCL). This yields peak ground acceleration of 0.64 g in the horizontal and of 0.53 g in the vertical direction. Response spectra were produced for the design of concrete structures and acceleration-time histories, compatible with the design site-specific response spectrum, for the design of the dams and slopes. The study area has experienced numerous large historical and 20th/21st century earthquakes with Ms between 0.4-7.6. Often earthquakes in this region cannot be related to a mapped surface faulting and they occur between the branches of the major faults. The Konar- Nari fault was considered as the most dominant structure in the deterministic analysis. Smaller faults around the sites are considered non-active or with low seismic potential. Considering that events of surface faulting may be separated by quiescent periods of 3000 to 5000 years, the choice of more conservative ground motion values derived from the Konar- Nari fault is justified. REFERENCES [1] GUTENBERG, B., RICHTER, C. F. Magnitude and Energy of Earthquakes. Annali di Geofisica, 1956, 9: 1–15. [2] KIJKO A., SELLEVOLL MA. Estimation of earthquake hazard parameters from incomplete data files. Part II. Incorporation of magnitude heterogeneity Bulletin of the Seismological Society of America, 1992. [3] CAMPBELL, K. W., BOZORGNIA, Y. Updated Near-Source Ground-Motion (Attenuation) Relations for the Horizontal and Vertical Components of Peak Ground Acceleration and Acceleration Response Spectra. Bulletin of the Seismological Society of America; 2003; v. 93; no. 1; p. 314-331; [4] AMBRASEYS, N., DOUGLAS, N. Equations for the Estimation of Strong Ground Motions from Shallow Crustal Earthquakes Using Data from Europe and the Middle East: Horizontal Peak Ground Acceleration and Spectral Acceleration. Bulletin of Earthquake Engineering. 2003, Volume 3, Number 1, 1-53. [5] BOORE, D. M., JOYNER, W. B. AND FUMAL, T. E. Equations for Estimating Horizontal Response Spectra and Peak Acceleration from Western North American Earthquakes, A Summary of Recent Work, Seism. Res. Lett. 1997, Vol. 68, No. 1, pp. 128-153. [6] MAHDAVIAN, A. Empirical evaluation of attenuation relations of peak ground acceleration in the Zagros and central Iran. First European 1109