Surface rupture during the 2010 M_w 7.1 darfield(canterbury) earthquake: Implications for fault rupture dynamics and seismic-hazard analysis

The September 2010 M_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 ± 0.5-km-long surface rupture across a lowrelief agricultural landscape. High-accuracy measurements of coseismic displacements were obtained at over 100 localities along the Greendale fault. Maximum net displacement (D_max) (5.3 ± 0.5 m) and average net displacement (D_avg) (2.5 ± 0.1 m) are anomalously large for an earthquake of this M_w. D_max / surface rupture length (SRL) and D_avg/SRL ratios are among the largest ever recorded for a continental strike-slip earthquake. "Geologically derived" estimates of moment magnitude (M_w ^G) are less than the seismologically derived M_w, derived using widely employed SRL-M_w scaling regressions. M_w G is greater than M_w using D_max- and D_avg-M_w regressions. The "geologically derived" static stress drop of 13.9 ± 3.7 MPa provides a context with which to compare this earthquake rupture to interplate and intraplate ruptures of similar M_w. This data set provides fundamental information on fault rupture processes relevant to seismic-hazard modeling in this region and analogous settings globally.