Previously Unknown Fault Shakes New Zealand's South Island

Abstract

At 4:35 A.M. local time on 4 September (1635 UTC, 3 September), a previously unrecognized fault system ruptured in the Canterbury region of New Zealand's South Island, producing a moment magnitude (Mw) 7.1 earthquake that caused widespread damage throughout the area. In stark contrast to the 2010 Mw 7.0 Haiti earthquake, no deaths occurred and only two injuries were reported despite the epicenter's location about 40 kilometers west of Christchurch (population ˜386,000). The Canterbury region now faces a rebuilding estimated to cost more than NZ$4 billion (US$2.95 billion).On the positive side, this earthquake has provided an opportunity to document the dynamics and effects of a major strike‐slip fault rupture in the absence of death or serious injury. The low‐relief and well‐maintained agricultural landscape of the Canterbury Plains helped scientists characterize very subtle earthquake‐related ground deformation at high resolution, helping to classify the earthquake's basic geological features [Quigley et al., 2010]. The prompt mobilization of collaborating scientific teams allowed for rapid data capture immediately after the earthquake, and new scientific programs directed at developing a greater understanding of this event are under way.