Insights into Distributed Plate Rates across the Walker Lane from GPS Geodesy

<p> 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&hyphen;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&deg;W) velocities define a velocity differential of 10.6&thinsp;&plusmn;&thinsp;0.5&thinsp;mm/yr between the western Basin and Range and the Sierra Nevada block, (2) there is ~2&thinsp;mm/yr of contemporary extension perpendicular to the normal faults of the Silver Peak&hyphen;Lone Mountain extensional complex, and (3) most of the observed discrepancy in long&hyphen; and short&hyphen;term slip rates occurs across Owens Valley. We believe the discrepancy is due to distributed strain and underestimated geologic slip rates.</p>