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SE9MUTWO SOISMIC Hazard ANIFIS Meth01109V <br /> where Mo is the moment rate and S is the slip rate. M,,has been related to moment magnitude, <br /> M,by Hanks and Kanamori(1979): <br /> M=2/3 log M,,- 10.7 (7) <br /> Using this relationship and the relative frequency of different magnitude events from the <br /> recurrence model, the slip rate can be used to estimate the absolute frequency of different <br /> magnitude events. <br /> The average return time for the characteristic or maximum magnitude event defines the high <br /> magnitude (low likelihood) end of the recurrence curve. When combined with the relative <br /> frequency of different magnitude events from the recurrence model, the recurrence curve is <br /> established. <br /> 2.3 DSHA APPROACH <br /> The deterministic approach involves the following steps: <br /> • Identification of the potential seismic sources that could affect the site and estimation of the <br /> maximum earthquake that could reasonably be expected from these sources. <br /> • Development of the range of maximum ground motions that are likely to occur at the site due <br /> to the maximum earthquake for each seismic source. <br /> • Selection of the controlling maximum earthquake with the potential for generating the <br /> strongest ground motions at the site. <br /> • Characterization of the controlling maximum earthquake in terms of PGA, acceleration <br /> response spectra, duration of strong ground shaking, and/or other parameters as deemed <br /> appropriate. <br /> The first step, which is required in any assessment of earthquake hazards, requires a <br /> characterization of all significant seismic sources that will produce ground motions of <br /> engineering significance at the site. Required parameters include fault location, geometry, and <br /> orientation; sense of slip; and maximum magnitude. In a deterministic analysis, no earthquake <br /> recurrence rate information is used. In a PSHA,this information is essential. <br /> 2.4 GROUND MOTION PREDICTION <br /> To characterize the ground motions at a specified site as a result of the seismic sources <br /> considered in the PSHA, we use empirical ground motion prediction models for spectral <br /> accelerations. The models used in this study were selected on the basis of the appropriateness of <br /> the site conditions and tectonic environment for which they were developed (Figure 4 and <br /> Section 4.3). <br /> The uncertainty in ground motion prediction was included in the PSHA by using the log-normal <br /> distribution about the median values as defined by the standard deviation associated with each <br /> ground motion prediction model. Three standard deviations about the median value are included <br /> in the analyses. <br /> um 5 <br />