Right‐lateral displacements and the Holocene slip rate associated with prehistoric earthquakes along the Southern Panamint Valley Fault Zone: Implications for southern Basin and Range tectonics and Coastal California deformation

Abstract

The N20øW-trending Panamint Valley fault zone is linked to the N60øW-trending Hunter Mountain strike-slip fault and the Saline Valley fault system, which represents one of the three major fault systems accommodating active crustal extension in the southern Great Basin. A 25 km-long zone of fault scarps along the southern Panamint valley fault zone is recognized as the surface rupture zone associated with the most recent prehistoric earthquake. The displacement associated with the most recent event, determined through six detailed topographic maps of offset features, is 3.2 +-0.5 m, and a number of larger offsets, in range of 6-7 m and 12 m, are also observed. If the larger displacements represent, respectively, two and three events, each of-•3 m, then the fault zone appears to be associated with a characteristic earthquake, which we estimate from the length of the rupture zone and the displacement to be between (Ms) 6.5 and 7.2. The Holocene slip rate is 2.36 +-0.79 mm/yr, is determined from the displacement of two alluvial features whose maximum age is estimated from pluvial shorelines. Assuming a characteristic earthquake model, the recurrence interval is between 860 and 2360 years. The Holocene slip rate appears to be similar to the 4 million year slip rate of 2-2.7 mm/yr (determined from the Hunter Mountain fault), which we suggest reflects the relatively constant tectonics in this region over the last 4 million years. We further speculate that this supports the San Andreas discrepancy in that the Holocene slip rate of the San Andreas fault probably represents its very-long term (several Ma) slip rate. The total slip vector of the southern Panamint Valley fault system is oriented toward -•N35øW, making this a predominantly strike-slip fault. In conjunction with the N60øW orientation of the Hunter mountain strike-slip fault, we suggest that the displacement vector for the southern Great Basin is toward the NW, consistent with results from VLBI data, rather than WNW as determined by combining VLBI and geological data. This in turn suggests that the coastal California deformation component involves, respectively, less shortening and more strike-slip displacement perpendicular and parallel to the San Andreas fault than is currently proposed. 4857 4858 ZHANG ET AL.' ACTIVE TECTONICS OF PANAMINT VALLEY PLATEAI ß 30 km j •ARLOCK

Acceleration and evolution of faults: An example from the Hunter Mountain–Panamint Valley fault zone, Eastern California

“…First, detailed studies of offset alluvial fans and young drainage channels allow definition of Pleistocene or Holocene-averaged rates, ranging from 2.4 to 4 mm/yr (Zhang et al, 1990;Oswald and Wesnousky, 2002). Second, long term average rates defined over the entire time span of fault activity are defined by dividing total offset (9.3 km) by the fault initiation age.…”

Transtensional analyses of fault patterns and strain provinces of the Eastern California shear zone–Walker Lane on the eastern margin of the Sierra Nevada microplate, California and Nevada

“…The dextral Little Lake Fault strikes slightly more northwest than the Airport Lake Fault and merges westwards with the Sierra Nevada Frontal Fault. The north-northwest striking dextral Panamint Valley and Death Valley Faults are sub-parallel to the Airport Lake Fault and the Sierra Nevada Frontal Fault Zone (Zhang et al 1990). Both faults were major structures in east -west extension from 12 to 6 Ma (Serpa and Pavlis 1996), however the northwest motion of the Sierra Nevada microplate beginning after this time made these faults favourably oriented to accommodate dextral motion.…”

“…These were connected by the Silver Peak -Lone Mountain extensional complex, which ceased activity also in the mid-Pliocene as transtensional deformation moved west and displacement transfer between the northern ECSZ and the Walker Lane was accommodated by the Mina Deflection (Oldow et al 2008). Transtension moved into the Saline Valley -Hunter Mountain -Panamint Valley Fault system at , 3.7 Ma (Hodges et al 1989;Zhang et al 1990), and into Coso and Owens Valley at , 3.4 and 3.0 Ma, respectively Stockli et al 2003). This time also marks the end of significant uplift of the southern Sierra Nevada range front and from , 3 to 3.4 Ma to the present, the edge of the Sierra Nevada block has served as the boundary of transtensional deformation in the Walker Lane and northern ECSZ Monastero et al 2002).…”

“…Active bimodal volcanism (Duffield et al 1980;Bacon 1982) and continuous lowlevel seismicity (, M3) (Unruh et al 2002) occur throughout the Coso region. To the east, the major active structures are the Panamint Valley Fault (Field Geophysics Course 1985 andBiehler 1987;Zhang et al 1990) and the Death Valley Fault Zone (Burchfiel and Stewart 1966;Hill and Troxel 1966;Wright and Troxel 1967).…”

Active tectonics and land-use strategies: a Palaeolithic example from northwest Greece

“…But they are not dead. Ample morphological evidence exists that several major earthquakes have occurred in the last 10,000-15,000 years (Zhang et al 1990). Similarly, historical data indicate that features between Turkey and Iran have had periods of major earthquakes lasting for tens of years separated by centuries of inactivity (Ambraseys 1989).…”