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However, as will be discussed, the Golden fault is too distant and has too low of a slip rate <br /> to contribute to the seismic hazard at the damsite. <br /> Mosquito and LeadWle Faults <br /> The Mosquito fault is a northeast-striking, steeply northwest-dipping normal fault that <br /> borders the western flank of the Mosquito Range (Plate 1). This fault has a total length of <br /> approximately 62 km (Kirkham and Rogers, 1981). The total length apparently includes a <br /> N40°E fault between Leadville and Tenmile dam (J. Unruh, William Lettis & Associates, <br /> personal communication, 1995) which we have not included. We estimate a total fault length <br /> of 53 km. The lengths of the northern and southern segments of the Mosquito fault are <br /> estimated to be 28 km and 25 km, respectively. The Tenmile dam is located just to the west <br /> of the boundary between the northern and southern segments (Plate 1). <br /> We have considered the faults around Leadville as a separate seismic source as they appear <br /> to be a transfer zone between the east-dipping Sawatch fault to the south and the west- <br /> dipping Mosquito fault to the north. The Leadville faults include several strands which span <br /> a distance of approximately 19 km from northeast to southwest. <br /> The mapped trace of the Mosquito fault in Kirkham and Rogers (1981) differs from the <br /> system of faults along the western margin of the Ten Mile Range and Mosquito Range as <br /> mapped by Tweto et al. (1978). The mapped trace shown on Plate 1 follows those mapped <br /> by Tweto et al. (1978). Near Leadville, the Mosquito and Leadville faults have a total <br /> vertical displacement of about 3660 m, and near the town of Climax, the displacement could <br /> be as great as 4720 m (Kirkham and Rogers, 1981). Evidence for Quaternary movement <br /> along this fault is relatively scarce. Scarps and anomalous features in moraines and colluvial <br /> deposits just south of Climax, near Tenmile dam, may reflect recent fault movement <br /> (Kirkham and Rogers, 1981), although this is uncertain. The Leadville faults deform late <br /> Neogene strata (Tweto et al., 1978). <br /> Since no slip rate data are available for the Mosquito fault and the Leadville faults, a slip <br /> rate of 0.1 mm/yr was assumed based on slip rate estimates for the Sawatch fault, which is <br /> the southern continuation of the northern Rio Grande rift. Mean maximum magnitudes are <br /> estimated to be Mw 6.7 for both segments of the Mosquito fault and Mw 7.0 for rupture of <br /> H:\CONTRACr\TENMILE\I I 11 M0412951500 <br />