Postseismic Corrected Walker Lane GPS velocities

The interseismic motion of GPS stations in a tectonically active, diffuse, strike-slip shear zone
provide constraints on the overall deformation budget that can be compared to the summation
of geologically-estimated fault slip rates to understand regional strain accommodation. The
Walker Lane GPS velocities in this dataset represent a subset of GPS stations included in the
Nevada Geodetic Laboratory MIDAS velocity solution (Blewitt et al., 2016, 2018; accessible at
http://geodesy.unr.edu/velocities/midas.NA12.txt, last accessed 11/19/2020) . This dataset
includes velocities for all GPS stations located between 34° N – 43° N latitude and 114° W –
123° W longitude with time series longer than 2.5 years from the semi-continuous MAGNET
network operated by the Nevada Geodetic Laboratory (Blewitt et al., 2009) and neighboring
continuous GPS stations. The MIDAS velocities are calculated using daily position data collected
through August 2019 presented in the NA12 reference frame (Blewitt et al., 2013) , and
corrected for the postseismic effects of historic ruptures in and surrounding the Walker Lane.
The MIDAS algorithm is a median trend estimator that mitigates both seasonality and step
discontinuities in the times series (Blewitt et al., 2016). The resulting velocities are insensitive to
the coseismic and postseismic effects of earthquakes that occurred after the midpoint of the
time series (Blewitt et al., 2016) , such as the July 2019 Ridgecrest, CA M w 6.4 and 7.1 sequence,
but must be corrected for the post-seismic effects of earthquakes that occurred prior to the
middle of time series, such as the historic surface rupturing earthquakes in Central Nevada
Seismic Belt and the 1993 Landers M w 7.3, and 1999 Hector Mine M w 7.0 events. We apply the
viscoelastic postseismic relaxation correction from Bormann et al. (2013) that was developed
using the method of Hammond et al. (2010) and the preferred western Basin and Range lower
crust (10 20.5 Pa-s) and upper mantle (10 19 Pa-s) viscosity model of Hammond et al. (2009) .
When using this dataset, please also cite Blewitt et al (2018) as the authors of the original
MIDAS NA12 reference frame velocity solution is the basis for our postseismic corrected Walker
Lane velocities:
Blewitt, G., Hammond, W.C., Kreemer, C., 2018. Harnessing the GPS Data Explosion for
Interdisciplinary Science. Eos. https://doi.org/10.1029/2018EO104623.

References:
Blewitt, G., Hammond, W.C., Kreemer, C., 2018. Harnessing the GPS Data Explosion for
Interdisciplinary Science. Eos. https://doi.org/10.1029/2018EO104623.
Blewitt, G., Kreemer, C., Hammond, W.C., Gazeaux, J., 2016. MIDAS robust trend estimator for
accurate GPS station velocities without step detection. Journal of Geophysical Research,
Solid Earth. https://doi.org/10.1002/2015JB012552.
Blewitt, G., Kreemer, C., Hammond, W.C., Goldfarb, J.M., 2013. Terrestrial reference frame
NA12 for crustal deformation studies in North America. Journal of Geodynamics.
https://doi.org/10.1016/j.jog.2013.08.004.
Bormann, J.M., Hammond, W.C., Kreemer, C., Blewitt, G., Jha, S., 2013. A Synoptic Model of
Fault Slip Rates in the Eastern California Shear Zone and Walker Lane from GPS Velocities

for Seismic Hazard Studies. Presented at the 2013 Seismological Society of America Annual
Meeting, Seismological Research Letters, Salt Lake City, UT, p. 323.
Hammond, W.C., Kreemer, C., Blewitt, G., 2009. Geodetic constraints on contemporary
deformation in the northern Walker Lane: 3. Postseismic relaxation in the Central Nevada
Seismic Belt., in: Late Cenozoic Structure and Evolution of the Great Basin-Sierra Nevada
Transition, Geological Society of America Special Paper 447.
https://doi.org/10.1130/2009.2447(03).
Hammond, W.C., Kreemer, C., Blewitt, G., Plag, H.-P., 2010a. Effect of viscoelastic postseismic
relaxation on estimates of interseismic crustal strain accumulation at Yucca Mountain,
Nevada. Geophysical Research Letters. https://doi.org/10.1029/2010GL042795.