Coseismic and early postseismic deformation of the 5 January 2013 Mw 7.5 Craig earthquake from static and kinematic GPS solutions

Static (low-rate, 30 s) and kinematic (high-rate, 1 s) Global Positioning System solutions are employed to investigate the near-field coseismic and early postseismic deformation associated with the 5 January 2013 Craig M (sub w) 7.5 earthquake. Based on the static solutions, the coseismic slip distribution has an average slip of approximately 6 m, a geodetic moment M (sub 0) of 1.5X10 (super 20) N.m, and a magnitude M (sub w) of 7.4. A comparison of the static and kinematic results indicates that early (first 4 days) postseismic deformation was small compared to the coseismic deformation. The postseismic transient can be characterized by a logarithmic decay function with an average decay time constant of about 56 days. Substantial postseismic deformation is observed over the first approximately 1.6 yrs of the earthquake and can be explained by afterslip on an adjacent segment of the fault to the southeast of the main coseismic rupture. Additional study will be needed to confirm whether afterslip is indeed the dominant mechanism causing postseismic motions or if another mechanism is also active.