Reactivated afterslip induced by a large regional earthquake, Fiordland, New Zealand

The evaluation of seismic hazard along active faults requires knowledge of the long term slip rate, the portions of the fault which are accumulating strain, and the magnitude, number, and location of past earthquakes. Aseismic slip will lower the long‐term seismic potential, but the distribution of seismic versus aseismic slip along faults is often poorly constrained. Changes to the local stress field may cause the distribution of slip to vary over time periods shorter than the seismic cycle, making it difficult to assess. Using interferometric synthetic aperture radar and GPS data, we present the coseismic and postseismic deformation associated with the 2007 Mw 6.8 George Sound (New Zealand) earthquake and the influence of the 2009 Mw 7.8 Dusky Sound earthquake on the postseismic deformation. Our results suggest that the stress change induced by the later magnitude 7.8 earthquake led to a period of reactivated aseismic slip along the Puysegur subduction interface which ruptured 2 years earlier.