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i b) Earthquake Magnitude - Data presented by McCalpin (19811, ' Menges (1987) and Losh (1982) indicate a likely rupture of 2 m along the Sangre de Cristo fault. Scarp enhance- ment due to erosion has likely caused the Kirkham and i Rogers single event offset (2.4 m) to be too Large. depending on the true fault segment length of the Sangre ' de Cristo fault (25 km - 50 km) and using a fault plane width of 12 km (Machette, 1986), the Likely maximum ' future earthquake magnitude is 6.8 to 7.0. As a point reference, the second Dixie Valley, Nevada eathquake ' of 1954 had a rupture segment length of 43 km, an offset of 2.1 m and a moment magnitude of 6.8. ' EARTHQUAKE HAZARD ANALYSIS ' Th hi i id ti f b f ject o t s sect on is to prov e an es mate o e o the earthquake hazard for the Battle Mountain Gold site. Several ' statistical models have been proposed in the literature to provide such an estimate for earthquake hazard ( the (probability of exceeding a given earthquake ground acceleration irr a given period of years), but most of these models require a relativly ' complete catalogue of historical seismicity. No earth<)uakes, however, have occurred in San Luis Valley during recorded history; in fact during a microearthquake study of thce Valley Keller and Adams (1976) were able to record only one r~icro- earthquake in eight days of recording, a remarkably low ' number when compared, for example, with the Intermountain Seismic Belt in Utah. A probability estimate can be obtained using the recurrence time as presented previously in Glass (1988). This re:;ults in ' a probability of experiencing a fault rupture within t:he next 100 years (assumed mine exposure time) of between 0.5 percent and 2.0 percent. As pointed out in Glass (1988), however, this approach assumes temporal independence of the earthquake process. In other words, it wouldn't matter whether 12 f J