Surface rupture during the 2010 M (sub w) 7.1 Darfield (Canterbury) earthquake; implications for fault rupture dynamics and seismic hazard analysis

The September 2010 M (sub w) 7.1 Darfield (Canterbury) earthquake in New Zealand is one of the best-recorded earthquakes of this magnitude. The earthquake occurred on a previously unidentified fault system and generated a 29.5+ or -0.5-km-long surface rupture across a low-relief agricultural landscape. High-accuracy measurements of coseismic displacements were obtained at over 100 localities along the Greendale fault. Maximum net displacement (D (sub max) ) (5.3+ or -0.5 m) and average net displacement (D (sub avg) ) (2.5+ or -0.1 m) are anomalously large for an earthquake of this M (sub w) . D (sub max) /surface rupture length (SRL) and D (sub avg) /SRL ratios are among the largest ever recorded for a continental strike-slip earthquake. "Geologically derived" estimates of moment magnitude (M (sub w) (super G) ) are less than the seismologically derived M (sub w) , derived using widely employed SRL-M (sub w) scaling regressions. M (sub w) (super G) is greater than M (sub w) using D (sub max) - and D (sub avg) -M (sub w) regressions. The "geologically derived" static stress drop of 13.9+ or -3.7 MPa provides a context with which to compare this earthquake rupture to interplate and intraplate ruptures of similar M (sub w) . This data set provides fundamental information on fault rupture processes relevant to seismic-hazard modeling in this region and analogous settings globally.