Anatomy of the 2009 Fiordland earthquake (Mw 7.8), South Island, New Zealand

We have analyzed the July 15, 2009, Fiordland earthquake (Mw 7.8), which occurred in the southwestern part of the South Island of New Zealand. This thrust-related earthquake in the southern Fiordland subduction zone is the largest New Zealand earthquake in the past 80 years. We have constrained a rupture model for this earthquake using coseismic offsets derived from the continuous geodetic network (Global Positioning System) of the New Zealand Institute of Geological and Nuclear Sciences (GNS Science). Our analysis concludes that this earthquake significantly increased the Coulomb stress on the overriding plate, particularly on the offshore portion of the Alpine fault.