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<br />a. Integrating the data for identified faults and other <br />seismotectonic structures with the project area seismicity data <br />to develop event/source correlations. <br /> <br />b. Developing and evaluating conceptual models to explain <br />significant earthquake events which do not correIa te with <br />identified faults or other seismotec tonic struc tures. <br /> <br />4. Local or Site Geology <br /> <br />Site specific geologic information should be developed to determine <br />the hazards from potential fault surface ruptures and to evaluate <br />material and structural responses to ground motions from the <br />expec ted range of seismic events. This information may be <br />obtained through the evaluation of published geologic reports, <br />field observations, and specific site investigations including <br />geologic mapping, trenching, drilling, material sampling and <br />testing, which should: <br /> <br />a. Define the geotechnical character, depositional history, <br />orientation, lateral extent, and thickness of soil units <br />beneath the site and on adjacent slopes. <br /> <br />b. Define the character, lateral extent, and thickness of rock <br />units at the site area. <br /> <br />c. De fine the struc tural geology of the site including rock <br />unit attitudes, faults and joint systems, folding and intrusive <br />bodies. <br /> <br />d. Define the age and activity of faults in the dam and reservoir <br />area. <br /> <br />e. Define the geohydrology of the site area including water table <br />conditions, soi 1 and rock transmissivity coefficients, and <br />recharge areas. <br /> <br />f. Identify existing and potential ground failure and subsidence, <br />including rock and soil stability, dispersive soil conditions, <br />and soil units with charac teristic s for potential liquefac tion. <br /> <br />g. Evaluate flooding potential due to seiche action by examination <br />of reservoir shape, topography, and slope stability conditions. <br /> <br />5. Seismic Attenuation <br /> <br />To complete the analysis of seismic potential, the energy <br />attenuation fac tors should be developed, so the energy transfer <br />potential between event sources and the proposed structure can be <br />evaluated. Because of the frequent inhomogeneity of areal and <br />cross-sectional geology, the attenuation assessment is difficult, <br />and to a large extent is based upon historical, empirical, and <br />theoretical data. The following procedures are most frequently <br />used : <br /> <br />-10- <br /> <br />------L__ <br />