Lawrence Berkeley National Laboratory

The 3 September 2016 Mw 5.8 Pawnee earthquake in northern Oklahoma is the largest earthquake ever recorded in Oklahoma. The coseismic deformation was measured with both Interferometric Synthetic Aperture Radar and Global Positioning System (GPS), with measureable signals of order 1 cm and 1 mm, respectively. We derive a coseismic slip model from Sentinel-1A and Radarsat 2 interferograms and GPS static offsets, dominated by distributed left-lateral strike slip on a primary west-northwest-east-southeast-trending subvertical plane, whereas strike slip is concentrated near the hypocenter (5.6 km depth), with maximum slip of ∼1 m located slightly east and down-dip of the hypocenter. Based on systematic misfits of observed interferogram line-of-sight (LoS) displacements, with LoS based on shear-dislocation models, a few decimeters of fault-zone collapse are inferred in the hypocentral region where coseismic slip was the largest. This may represent the postseismic migration of large volumes of fluid away from the high-slip areas, made possible by the creation of a temporary high-permeability damage zone around the fault.