This special issue of the New Zealand Journal of Geology and Geophysics addresses different facets of the Canterbury earthquake sequence that commenced with the MW 7.1 Darfield (Canterbury) earthquake on 4 September 2010 and continued during a prolonged aftershock sequence that included the fatal MW 6.2 Christchurch earthquake of 22 February 2011. The timespan of the sequence referred to in the special issue title has been adopted because the studies presented here mostly address events of 2010 and 2011. However, as of mid-2012, this aftershock sequence continues to produce potentially damaging (ML 4) earthquakes in the vicinity of Christchurch city and in the surrounding region. In compiling this special issue, our goal has been to facilitate broad-ranging documentation and analysis of the characteristics and impacts of the Canterbury earthquake sequence, with a principal focus on the Darfield and Christchurch earthquakes. The first six papers discuss the geological, structural and tectonic contexts for the seismicity based on field mapping, geophysical studies and an analysis of historical seismicity. The next two papers document the location and amount of slip on the major faults that ruptured during the sequence. The following four papers characterise the hydrological, geological and geomorphic impacts of the largest earthquakes. These papers are followed by four papers addressing seismological aspects of the sequence as a whole. The final paper in the volume addresses the role of geoscientific research and geoscientists themselves in the governmental and societal response to and recovery from these earthquakes. We hope that this special issue will provide a long-lasting and influential repository of important scientific results that will be of use to not only the scientific community, but also to educators, policy-makers and the media throughout New Zealand and overseas. The opening paper by Campbell et al. synthesises several decades of field-based research into active deformation beneath the Canterbury Plains and the eastern foothills of the Southern Alps. The authors present structural and geomorphic evidence for the eastward propagation of kinematically linked east-striking transpressional dextral strike-slip faults and NE-striking thrust faults in northern Canterbury, which provide more evolved analogues for the fault system that ruptured in the Darfield earthquake. Campbell et al. argue that east-striking faults such as the Greendale Fault, a previously unrecognised fault that ruptured during the Darfield earthquake, seem to be either entirely activated or selectively accelerated to the surface, in association with the major fault propagation folds of the thrust system. The authors suggest that strike-slip faults will tend to emerge while related thrust faults remain blind, that slip distributions on the strike-slip faults will be strongly controlled by the geometry and displacement rates on the hidden adjacent thrusts and that pre-historic surface rupture lengths will thus under-represent the rupture areas of the associated earthquakes. All of these conclusions have implications for deducing the magnitude potential of earthquake sources from the geological record of faulting. The tectonic history of the region and its detailed subsurface structure are also discussed by Jongens et al. and Ghisetti & Sibson based on data from regional maps, gravity, and oil exploration seismic lines and wells. Jongens et al. describe the subsurface structure of the whole Canterbury plains and link it with the geomorphic expressions of active faults (or lack thereof). The authors demonstrate that Late Cretaceous east-striking normal faults have been reactivated as strike-slip/reverse faults during the late Cenozoic and propose that the Greendale fault is one of these reactivated structures. The paper also suggests that NE-striking reverse faults close to the ranges are likely to be newly formed and to have played a role in the deformation associated with the recent and ongoing seismicity. Ghisetti & Sibson describe a similar reactivation history for the Ashley fault, which they infer to be a close mechanical analogue to the Greendale Fault. The authors document similarities between the orientation and predominant sense of movement of different fault segments delineated by the current seismicity (including the Greendale Fault) and the general structures of the area (including the Ashley Fault). The orientations and senses of motion of these structures are consistent with those expected given the prevailing stress regime. Ghisetti & Sibson further describe New Zealand Journal of Geology and Geophysics Vol. 55, No. 3, September 2012, 151 154