GPS, slip rates, Walker Lane, Owens Valley, tectonics, plate boundary, GPS, slip rates, Walker Lane, Owens Valley, tectonics, plate boundary
Digital Object Identifier (DOI)
Contemporary geodetic slip rates are observed to be approximately two times greater than late Pleistocene geologic slip rates across the southern Walker Lane. Using a dense GPS network, we compare the present‐day crustal velocities to observed geologic slip rates in the region. We find that the Walker Lane is characterized by a smooth transition from westward extension in the Basin and Range to northwestward motion of the Sierra Nevada block. The GPS velocity field indicates that (1) plate parallel (N37°W) velocities define a velocity differential of 10.6 ± 0.5 mm/yr between the western Basin and Range and the Sierra Nevada block, (2) there is ~2 mm/yr of contemporary extension perpendicular to the normal faults of the Silver Peak‐Lone Mountain extensional complex, and (3) most of the observed discrepancy in long‐ and short‐term slip rates occurs across Owens Valley. We believe the discrepancy is due to distributed strain and underestimated geologic slip rates.
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Citation / Publisher Attribution
Geophysical Research Letters, v. 40, issue 17, p. 4620-4624
©2013. American Geophysical Union. All Rights Reserved.
Scholar Commons Citation
Lifton, Zachery M.; Newman, Andrew V.; Frankel, Kurt L.; Johnson, Christopher W.; and Dixon, Timothy H., "Insights into Distributed Plate Rates across the Walker Lane from GPS Geodesy" (2013). School of Geosciences Faculty and Staff Publications. 1544.
Plate parallel velocity profile dislocation models across most of the Pacific‐North America plate boundary. Black filled circles and black error bars are data from this study. The profile crosses the San Andreas Fault (SAF), the Sierra Nevada Frontal Fault (SNFF), the White Mountains Fault (WMF), and the Death Valley‐Fish Lake Valley Fault (DVFLVF). The dislocation model is similar to those described in the main text but here includes the SAF. The solid black line is the best fit model, with 1 km locking depth of the SAF and 15 km locking depth on the SNFF, WMF, and DVFLVF; the dashed black line is the solution for 15 km locking depth on all faults. The sharp gradient across the SAF is due to the proximity to the creeping Parkfield section, which contributes coseismic slip to our measurements of interseismic strain. The dislocation model requires an unreasonably shallow apparent locking depth to account for the coseismic contributions. Our GPS velocities are relative to North America using the Euler pole from the MORVEL reference frame [DeMets et al., 2010]. The absolute amplitude of the displacement field will be shifted ~0.5 mm/yr to the southeast if we use the GEODVEL reference frame [Argus et al., 2010]. For comparison, we also show profile 4 from McCaffrey  (gray‐filled circles, gray error bars, and gray curve). McCaffrey’s  profile crosses the plate boundary further south, at ~36°N, and shows deformation spread over a wider region and a less distinct plateau of velocities across the Sierra Nevada block.
fig_s2.eps (1906 kB)
Walker Lane GPS velocity field with sited colored by transect. Colors correspond to profiles in Figure S3. CVF—Clayton Valley Fault; DV‐FLVF—Death Valley‐Fish Lake Valley Fault; EIF—Eastern Inyo Fault; EPF—Emigrant Peak Fault; LMF—Lone Mountain Fault; LVC—Long Valley Caldera; SNFF—Sierra Nevada Frontal Fault; SPLM—Silver Peak‐Lone Mountain extensional complex; WMF—White Mountains Fault.
fig_s3.eps (530 kB)
Additional plate‐parallel and plate‐normal velocity profiles along transects perpendicular to plate motion. (C) and (D) are duplicated from Figure 2 and are included here for completeness. Circle colors correspond to circle colors on Figure S2. DV‐FLVF—Death Valley‐Fish Lake Valley Fault; EIF—Eastern Inyo Fault; LVC—Long Valley Caldera; SNFF—Sierra Nevada Frontal Fault; SPLM—Silver Peak‐Lone Mountain extensional complex; WMF—White Mountains Fault.
table_s1.doc (127 kB)
GPS station positions and velocities.
lifton_etal_gps_suppl_readme_rev1.doc (37 kB)