Block modeling of crustal deformation across the Sierra Nevada, northern Walker Lane, Basin and Range transition, western America using GPS measurement.
Speaker: Chi-Fang Lee Adviser: Wu-Lung Chang
Abstract
Authors infer rates of crustal deformation in the northern Walker Lane (NWL) and western Basin and Range using data from campaign stations (2000-2004), the Mobile Array of GPS for Nevada transtension (2004-2010) and other continuous GPS networks including the EarthScope Plate Boundary Observatory. They use this data to constrain a block model to estimate fault slip rates. The data segregate the NWL into domains based on differences in deformation rate, pattern, and style. Deformation is transtensional, with highest rates near the western and eastern edges of the NWL. Some basins, e.g., Tahoe, experience shear deformation and extension. Normal slip is distributed throughout the NWL and Basin and Range, where 11 subparallel range‐bounding normal fault systems have an average horizontal extension rate of 0.1 mm/yr. Comparison between geologic and geodetic slip rates indicates that out of 12 published geologic rates, 10 agree with geodetic rates to within uncertainties. This suggests that smaller crustal blocks move steadily, similar to larger lithospheric plates, and that geodetic measurements of slip rates are reliable in zones of complex crustal deformation. For the two slip rates that disagree, geologic rates are greater. The vertical axis rotation rate of the Carson domain is -1.3 ± 0.1°/My clockwise, lower than the 3° to 6°/My obtained in paleomagnetic measurements. This suggests that vertical axis rotation rates may have decreased over the last 9– 13 My as the role of faulting has increased at the expense of rigid rotations.
References
William C. Hammond and Wayne Thatcher (2007), Crustal deformation across the Sierra Nevada, northern Walker Lane, Basin and Range transition, western United States measured with GPS, 2000–2004 ,J. Geophys. Res., 112, B05411, doi:10.1029/2006JB004625.
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William C. Hammond, Geoffrey Blewitt, and Corné Kreemer (2011), Block modeling of crustal deformation of the northern Walker Lane and Basin and Range from GPS velocities, J. Geophys. Res., 116, B04402, doi:10.1029/2010JB007817.