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Interseismic deformation and geologic evolution of the Death Valley Fault Zone

Cecilia Del Pardo, Bridget R. Smith-Konter, Laura F. Serpa, Cornelis W. Kreemer, Geoffrey Blewitt, & Pat Hammond

Published June 2012, SCEC Contribution #1514

The Death Valley Fault Zone (DVFZ), located in southeastern California, is an active fault system with an evolved pull-apart basin that has been deforming over the past 6 Myr. We present a study of the interseismic motion and long-term stress accumulation rates to better understand the nature of both past and present-day loading conditions of the DVFZ. Using a 3-D semi-analytic viscoelastic deformation model, combined with geodetic velocities derived from the UNR MAGNET network and SCEC CMMv4 GPS data, we establish best-fitting model parameters for interseismic slip rate and apparent locking depth for 4 segments of the DVFZ. Our preferred model provides a good fit to the data (0.6 mm/yr and 1.1 mm/yr RMS misfit in the fault-perpendicular and fault-parallel directions, respectively) and yields apparent locking depths between 9 – 17 km and strike-slip rates of 3 – 7 mm/yr. We also determine subsidence and extension rates of 0.3 – 0.5 mm/yr and 1.0 – 1.2 mm/yr, respectively, in the pull-apart basin region. With these modeled fault parameters, we construct a DVFZ evolution model for the last 6 Myr that recreates the motion of the fault blocks involved in the formation of the present-day geological structures in Death Valley. Finally, using Coulomb stress accumulation rates derived from our model (0.2 – 0.5 MPa/100yr), combined with earthquake recurrence interval estimates of 500 to 2600 years, we assess present day seismic hazards of the DVFZ with calculated moment magnitudes ranging from 6.7 – 7.6 for the DVFZ segments, with the highest earthquake moment identified along the northern segment.

Del Pardo, C., Smith-Konter, B. R., Serpa, L. F., Kreemer, C. W., Blewitt, G., & Hammond, P. (2012). Interseismic deformation and geologic evolution of the Death Valley Fault Zone . Journal of Geophysical Research: Solid Earth, 117(B6), B06404. doi: 10.1029/2011JB008552.