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<br />r <br />where ot(m°) is the annual frequency of occurrence of earthquakes greater than the minimum <br />magnitude, m°; b is the Gutenberg-Richter pazameter defining the slope of the recurrence <br />curve; and m" is the maximum magnitude event that can occur on the source. A m° 5 was <br />used for the hazard calculations because smaller events are not considered likely to produce <br />ground motions with sufficient energy to damage well designed structures. <br />For the characteristic model, the number of events exceeding a given magnitude is the sum <br />of the characteristic events and the non-characteristic events. The characteristic events are <br />distributed uniformly overt 0.3 magnitude unit around the characteristic magnitude <br />(Figure 1) and the remainder of the moment rate is distributed exponentially using the above <br />equation with a maximum magnitude one unit lower than the characteristic magnitude. <br />The recurrence rates for the fault sources are defined by the slip rate for the maximum or <br />' characteristic event and the recurrence b-value. The slip rate is used to calculate the moment <br />rate on the fault using the following equation defining the seismic moment. <br />Ivl, = µ A D (5) <br />where Iv1o is the seismic moment, µ is the sheaz modulus, A is the area of the rupture plane, <br />and D is the slip on the plane. Dividing both sides of the equation by time n:salts in the <br />moment rate as a function of slip rate: <br />M=µAS (6) <br />where M is the moment rate and S is the slip rate. lvta has been related to Mw b~~ Hanks and <br />Kanamori (1979): <br />My = 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 /> <br />N:\CONiRACI\23G561.DUH6 () M0309951609 <br />