Strain Partitioning Across the Eastern California Shear Zone
Relative motion between the Pacific and North America plates at the latitude of central
California is ~50 mm/yr [ DeMets and Dixon , 1999]. Approximately 12 mm/yr is accommodated in a complex system of primarily northwest trending dextral strike-slip faults known as the Eastern
California Shear Zone (ECSZ) [ Sauber et al.
, 1986; Minster and Jordan , 1987; Dokka and Travis , 1990,
1990; Oldow et al.
, 1994; Sauber , 1994; Dixon et al.
, 1995; Reheis and Dixon , 1996; Bennett et al.
,
1998; Thatcher et al.
, 1999; Bennett et al.
, 2003]. This talk focuses on the Owens Valley (OV),
Panamint Valley (PV) and Death Valley (DV)-Furnace Creek (FC) faults in the region north of the
Garlock fault and south of the Mina Deflection.
Geologic and geodetic rates and recurrence intervals for each of these faults differ significantly.
One explanation is that geodetically determined fault properties are calculated using models. If the geodetic model does not take into consideration all parameters affecting the strain, the interpretation of the model may be biased. Traditional models of strike-slip faults do not account for laterally varying material properties or geometries. In the case of the ECSZ, surface fault traces show that these faults are not parallel to one another and thus may affect strain partitioning. Also, anomalously high heat flow may indicate either a thinned brittle upper crust and/or lower viscosities, causing variations in material properties. Partitioning of strain between these faults is important because of their location to Yucca
Mountain, a proposed nuclear waste repository east of the DV fault. As a preliminary analysis, I will present two transects of GPS data across the ECSZ in combination with 2D finite element models.