HR: 09:45h
AN: T51A-07    [PDF]
TI: Pacific-North America plate boundary deformation in the greater Salton Trough area, southern California, USA
AU: * Fay, N P
EM: nfay@newberry.uoregon.edu
AF: University of Oregon, Department of Geological Sciences, Eugene, OR 97403 United States
AU: Humphreys, E D
EM: gene@newberry.uoregon.edu
AF: University of Oregon, Department of Geological Sciences, Eugene, OR 97403 United States
AB: The general kinematic nature of the Pacific-North American plate boundary in southern California is well described by long-term geologic fault slip-rate estimates and short-term geodetic measurements of surface displacement rates. In general, these data sets agree, often through simple kinematic models. There are, however, interesting differences in the greater Salton Trough/Imperial valley (a sedimentary basin). Geologic estimates of slip-rate on the block-bounding faults (e.g., the southern San Andreas, San Jacinto, Imperial, etc.) favor the San Andreas as the major plate-boundary fault. Recent geodetic strain estimates suggest the San Jacinto fault accommodates as much, or more, strain than the San Andreas fault. These discrepancies could reflect the disparate time scales over which geology and geodesy measure crustal deformation. Also, significant lateral and vertical variations in crustal rheology (elastic properties such as shear strength), which thus far have not been included in kinematic models of geodetic data in this area, may have important effects on interpretation of geodetic displacement rates. We present preliminary results of a finite element model driven by well-known far-field plate motions to test the influence of variations in crustal rheology on observed geodetic displacements. Crustal elastic properties are calculated from seismic velocity estimates from the SCEC 3D velocity model. Model surface displacement rates are compared to the SCEC crustal motion map.
DE: 1206 Crustal movements--interplate (8155)
DE: 8105 Continental margins and sedimentary basins
DE: 8110 Continental tectonics--general (0905)
DE: 8120 Dynamics of lithosphere and mantle--general
DE: 8155 Plate motions--general
SC: Tectonophysics [T]
MN: 2003 Fall Meeting