Block modeling of crustal deformation of the northern Walker Lane and Basin and Range from GPS velocities

Abstract

[1] We infer rates of crustal deformation in the northern Walker Lane (NWL) and western Basin and Range using data from the Mobile Array of GPS for Nevada transtension, and other continuous GPS networks including the EarthScope Plate Boundary Observatory. We present 224 new GPS velocities, correct them for the effects of viscoelastic postseismic relaxation, and use them 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.

Uniform California Earthquake Rupture Forecast, Version 3 (UCERF3)--The Time-Independent Model

“…The input models were updates of McCaffrey's DefNode (McCaffrey, 2002(McCaffrey, , 2005, Hammond's block model (Hammond et al, 2011), Johnson's quasi-block model (Johnson and Fukuda, 2010), and special (more block-like) versions of NeoKinema and Zeng's model. The averaging used the slip rates from all five block-model inversions as data in a unified block model inversion.…”

The present-day number of tectonic plates

“…The variation in area of these 159 plates is by a factor of over 380,000-from 104 Mm 2 for the Pacific plate to 273 km 2 for plate 5 of Hammond et al (2011). This huge variation calls for a logarithmic axis Fig.…”

“…They also used observations from the Plate Boundary Observatory GPS stations which consist of a network of 1100 permanent, continuously operating GPS stations, many of which provide data at high rate and in real time, and some of which are within the area studied. Hammond and Thatcher (2007) studied small plates which covered much of the area described by Hammond et al (2011). One plate which was not completely covered by the area in Hammond et al (2011) was the Mohawk plate.…”

“…Hammond and Thatcher (2007) studied small plates which covered much of the area described by Hammond et al (2011). One plate which was not completely covered by the area in Hammond et al (2011) was the Mohawk plate. This plate had complete boundaries in Hammond and Thatcher (2007).…”

“…This represents almost 4000 data points. The plates used by McCaffrey (2005) Hammond et al (2011) arrived at 31 plates whose boundaries were completely known (see Additional file 1: Table S4) out of a total of 60 plates. The smallest plate from Hammond et al (2011) was 1.8 times smaller in area than the Plieto plate, the smallest plate in Bird and Rosenstock's list.…”