Text S1.  Faults of the Northern Eastern California Shear Zone
S1.1  Owens Valley Fault Zone  
      In the west, the strike-slip component of motion through Owens Valley is accommodated by the Owens Valley fault zone (OVFZ), which last ruptured during the 1872 Mw approximately 7.6 Owens Valley earthquake, and its northern continuation, the White Mountains fault system [Lubetkin and Clark, 1988; Beanland and Clark, 1994].  The last major seismic event along the White Mountains fault zone was a swarm in 1986 that included Mw 5.7 and Mw 6.3 earthquakes in Chalfant Valley [Smith and Priestly, 2000].  Geologic slip rate estimates of the OVFZ range from 0.7 to 3.8 mm/yr [Lubetkin and Clark, 1988; Beanland and Clark, 1994; Lee et al., 2001a].  Geologic rates on the White Mountains fault zone are similar to the OVFZ, ranging from 0.7 to 2.8 mm/yr [dePolo, 1989; Schroeder, 2003].  Geodetic rates for the OVFZ are higher, but vary dramatically.  Studies using an elastic half-space model estimate rates of 4.1 to 8 mm/yr [Savage et al., 1990; Savage and Lisowski, 1995; Dixon et al., 1995; Dixon et al., 2000; Gan et al., 2000; Miller et al., 2001; McClusky et al., 2001].  In contrast, Dixon et al. [2003] used an elastic-viscoelastic half-space model to calculate a geodetic rate of 2.1 +/- 0.3 mm/yr, which agrees better with the geologic data.
      
S1.2  Panamint Valley, Ash Hill, and Hunter Mountain Fault Zones
      East of Owens Valley, the Ash Hill and Panamint Valley fault zones accommodate slip in Panamint Valley.  These fault zones transfer slip northward to the Hunter Mountain-Saline Valley fault zone (HMFZ).  The Ash Hill fault zone, which extends for ~50 km along the west side of Panamint Valley, has a geologic slip rate of 0.3 to 0.5 mm/yr based on the offset of putative mid- to late-Pleistocene (approximately 125 to 150 ka) pluvial lake shorelines and a approximately 4 Ma basalt flow [Densmore and Anderson, 1997]. The oblique dextral-normal Panamint Valley fault zone bounds the entire eastern piedmont of Panamint Valley. On the basis of measured Holocene alluvial fan offsets, Zhang et al. [1990] calculated a strike-slip rate of 2.4 +/- 0.8 mm/yr. This rate, when combined with the dextral slip rate on the adjacent Ash Hill fault, is slightly slower than the 15 ka rate of 3.3 to 4.0 mm/yr estimated for the HMFZ to the north, which is responsible for transferring slip from Panamint Valley into Saline Valley [Oswald and Wesnousky, 2002].  Sternloff [1988] measured a 1.2 Ma rate of 3.2 to 3.4 mm/yr for the HMFZ, whereas Burchfiel et al. [1987] and Sternloff [1988] measured a slower, longer-term rate of 1.3 to 2.3 mm/yr on the basis of an offset 4.6 Ma basalt flow.
      
S1.3  Stateline Fault Zone
      Still farther east, the Stateline fault system (SLFZ) along the Nevada-California border extends north through Mesquite and Pahrump Valleys to a complex transfer zone in the Amargosa Valley, finally trending to the north-northwest toward the Yucca Mountain area as a diffuse zone of faults (Figure 2) [Schweickert and Lahren, 1997; Guest et al., 2005].  The SLFZ forms a greater than 90-km-long system of NW-trending fault scarps with associated pressure ridges and sag ponds [Guest et al., 2005].  On either side of the Quaternary scarps in Mesquite Valley, the fault offsets a 12.6 Ma volcanic breccia deposit 28 +/- 3 km, yielding a post-mid-Miocene average slip rate of 2.2 +/- 0.2 mm/yr [Guest et al., 2005].  Northwestward in the Amargosa Valley area, a simple through-going fault in Quaternary deposits is not observed, however diffuse faulting, aligned springs and other lines of evidence led Schweickert and Lahren [1997] to suggest an active fault with 1 to 2 mm/yr of slip may be present.  Data from a dense, continuous GPS network across the Amargosa Valley/Yucca Mountain region indicate a zone of N20W right-lateral shear of 1.2 +/- 0.2 mm/yr is present, with strain focused just east of Yucca Mountain [Wernicke et al., 2004].  Simple dislocation models of these data that include both the Stateline structure and the NDVFZ suggest geodetically determined slip rates of 0.9 mm/yr and 2.8 mm/yr, respectively [Wernicke et al., 2004], although other, more complex models involving seismic cycle effects are clearly possible [e.g. LaFemina et al., 2005; Schmalzle et al., 2005].
      
S1.4  Dip-slip Transfer Faults
      In addition to the major north-trending dextral faults, a number of northeast-trending faults transfer slip between faults of the Owens and Panamint Valley fault systems and the Death Valley fault system (Figure 2) [Dixon et al., 1995].  These predominantly down-to-the-northwest extensional faults include the Deep Springs, Towne Pass, and Tin Mountain faults [Dixon et al., 1995; Lee et al., 2001b; Klinger, 2001].  Geologic slip rates are poorly defined for most of these structures, with the exception of the Deep Springs fault, where Lee et al. [2001b] measured an extension rate of 0.2 to 0.7 mm/yr. Long-term slip rates of 3.2 to 3.4 mm/yr have been estimated for a complex system of normal faults cutting basalt flows along the northeast side of Saline Valley (Figure 2) [Sternloff, 1988].  
      
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