The predominant approach for modeling faults in the Earth’s crust represents them as elastic dislocations, extending downdip into the lower crust, where the faults slip continuously. The resulting surface deformation features strain accumulation concentrated across locked faults during the interseismic period. An alternative model proposes faults confined to the elastic crust, with surface deformation driven by a wide zone of distributed shear underneath. Using high-precision GPS data, we analyze deformation profiles across the Walker Lane (WL), USA. The WL is a transtensional region of complex faulting, which delineates the western edge of the Basin and Range province and accommodates a significant portion of the Pacific-North American plate boundary deformation budget. Despite a dense geodetic network surveyed collectively for nearly 20 years, horizontal velocities reveal no evidence of localized strain rate accumulation across fault surface expressions. Instead, deformation within the shear zone is uniformly linear, suggesting that the surface velocities reflect distributed shear within the ductile crust rather than discrete fault deformation. This implies no downdip fault extension below the seismogenic layer. The shear zone, bound by the Sierra Nevada crest in the west, is 172±6 km wide in the northernmost WL narrowing to 116±4 km in the central WL. This study’s conclusion challenges the assumption of the presence of dislocations in the lower crust when estimating geodetic slip rates, suggesting that slip rates are instead controlled by the fault’s position and orientation within the shear zone. This has important implications for quantifying seismic hazards in regions with complex fault systems.

Great Salt Lake (GSL), Utah, lost 1.89 +/- 0.04 meters of water during the 2012 to 2016 drought. During this timeframe, data from the GRACE mission do not detect anomalous mass loss, but nearby Global Positioning System (GPS) stations show significant shifts in position. We find that crustal deformation, from unloading the Earth’s crust with the observed GSL water loss alone, does not explain the GPS displacements, suggesting contributions from additional water storage loss surrounding GSL. This study applies a damped least squares inversion to the 3D GPS displacements to test a range of distributions of radial mass load rings to fit the observations. When considering the horizontal and vertical displacements simultaneously, we find the most realistic distribution of water loss while also resolving the observed water loss of the lake. Our preferred model identifies radially decreasing mass loss up to 64 km from the lake. The contribution of exterior groundwater loss is substantial (10.9 +/- 2.8 km^3 vs. 5.5 +/- 1.0 km^3 on the lake), and greatly improves the fit to the observations. Nearby groundwater wells exhibit significant water loss during the drought, which substantiates the presence of significant water loss outside of the lake, but also highlights greater spatial variation than our model can resolve. We observe seismicity modulation within the inferred load region, while the region outside the (un)loading reveals no significant modulation. Drier periods exhibit higher quantities of events than wetter periods and changes in trend of the earthquake rate are correlated with regional mass trends.