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i <br /> <br /> <br /> where D is the expected fault displacement, S is the background, <br /> or Long term, deformation rate (0.4 mm/yr to 0.1 mm/y- from <br /> Figure 1) and C is the aseismic creep rate. Table III presents <br /> the probability of experiencing a fault rupture over the next <br /> 50 and 100 year period on the San Luis segment of the Sangre <br /> de Cristo fault. The probability is calculated as R-1 times the <br /> span in years. Such a calculation assumes that earthquakes are <br /> uncorrelated in time. The aseismic creep rate is assumed to be <br /> zero. From Table III the probability of experiencing ~, fault <br /> rupture along the Sangre de Cristo fault segment near the Battle <br /> Mountain Gold site (M = 7.1 -- 7.6) ranges from one-hs.lf of <br /> one percent to two percent for the next 100 year period. <br /> The assumption that earthquakes are uncorrelated is not <br />i <br />t <br />i <br />id <br />ll <br />i <br />h <br /> necessary or appropr <br />a <br />e, espec <br />y cons <br />a <br />er <br />ng an area suc <br /> as San Luis Valley which displays long periods of time between <br />' earthquakes. If one assumes that earthquakes relieve strain <br /> energy associated with tectonic processes, then the time <br />' intervals between earthquakes must correspond to periods of <br /> strain accumulation. Once the strain progresses to a point of <br /> failure along the fault, an earthquake occurs again to release <br /> the strain energy. Hence, as the Length of time increases since <br /> the last earthquake, the probability of experiencing another <br />h <br />ld i <br /> one s <br />ou <br />ncrease. <br /> One approach that accounts for these physical arguments <br /> is the semi-Markhov approach proposed by Patwardhan et al.(1980). <br /> This approach should be applied to this project. To obtain a <br /> rough idea of how this approach would affect the earthquake <br /> probability for the Sangre de Cristo fault, I have provided <br />I Figure 2. Figure 2 is redrafted from CLuff et al.(1980), and <br /> shows a semi-Markhov analysis of a portion of the Wasatch fault <br /> in Utah. The Wasatch fault appears more active than the Sangre <br /> <br />i <br />