As of October 2005, the semipermanent Global Positioning System (GPS) network called MAGNET (Mobile Array of GPS for Nevada Transtension) included 60 stations and spanned 160 km (N-S) × 260 km (E-W) across the northern Walker Lane and central Nevada seismic belt. MAGNET was designed as a cheaper, higher-density alternative to permanent networks in order to deliver high-accuracy velocities more rapidly than campaigns. The mean nearest-neighbor spacing is 19 km (13–31 km range). At each site, the design facilitates equipment installation and pickup within minutes, with the antenna mounted precisely at the same location to mitigate eccentricity error and intersession multipath variation. Each site has been occupied ~50% of the time to sample seasonal signals. Using a custom regional filtering technique to process 1.5 yr of intermittent time series, the longest-running sites are assessed to have velocity accuracies of ~1 mm/yr. The mean weekly repeatability is 0.5 mm in longitude, 0.6 mm in latitude, and 2.1 mm in height. Within a few years, MAGNET will characterize strain partitioning in the northern Walker Lane to improve models of (1) geothermal activity, which is largely amagmatic in the Great Basin, (2) seismic hazard, (3) the ways in which northern Walker Lane accommodates strain between the Sierra Nevada block and the extending Basin and Range Province, and (4) Neogene development of the northern Walker Lane and its broader role in the ongoing evolution of the Pacific–North America plate-boundary system. MAGNET’s design is generally applicable to regions with an abundance of vehicle-accessible rock outcrops and could be replicated elsewhere.

We present a velocity and strain rate model for the northern Walker Lane derived from a compilation of geodetic velocities and corrected for transient effects owing to historic earthquakes on the Central Nevada seismic belt. We find that from 37°N to 40°N, the Walker Lane is characterized by an ~100-km-wide zone with near-constant strain rates associated with ~10 mm yr −1 total motion across the zone. The strain rates depict predominantly shear deformation, but south of 39°N, the extensional component of the strain rate tensor increases and thus reflects more of a transtensional domain there. We conclude that this transtension is a kinematic consequence of the motion of the Sierra Nevada–Great Valley block, which is not parallel to its eastern margin, i.e., the eastern Sierra front, south of 39°N. While the orientations of several normal and strike-slip faults in the Walker Lane region are consistent with the strain rate model results at several places, the mode and rate at which geologic structures accommodate the deformation are less clear. Left-lateral faulting and clockwise rotations there may contribute to the accommodation of the velocity gradient tensor field, and most normal faults are properly oriented to accommodate some component of the regional shear strain, but significant additional right-lateral strike-slip faulting is required to accommodate the majority of the 10 mm yr −1 relative motion. Overall, the along-strike variation in the active tectonics of Walker Lane suggests that (1) various mechanisms are at play to accommodate the shear, (2) parts of the surface tectonics may (still) be in an early stage of development, and (3) inherited structural grain can have a dominant control on the strain accommodation mechanism.