Abstract
I will present a wide ranging summary of what happened in these very "costly" earthquakes, from the work of dozens of scientists at GNS Science. I will discuss the seismology of both of these earthquakes, and present an overview of surface rupture and slip on the Greendale Fault during the Darfield earthquake. In particular, seismology and geodesy reveal unusually complex source mechanisms in both of the events. These earthquakes have produced an extraordinary number of aftershocks that have heavily impacted the local community in Christchurch. I will discuss the implications that these aftershocks have for our understanding of this earthquake sequence, as well the outreach efforts geoscientists in New Zealand have made to help the public understand what has happened, and what they might expect to happen in the future. Intriguing hydrological transients in the Canterbury Plains have also occurred as a result of this earthquake sequence and I will discuss those. Some of the most notable damage in the Christchurch area has been the result of local site effects on the seismic shaking, liquefaction, and rock falls. The February event produced some of the largest ground motions ever recorded. These extreme ground motions appear to be largely the result of (a) unusually high energy release, (b) strong directivity towards Christchurch, and (c) energy released during a "slap down" or "trampoline" effect where different geological layers beneath Christchurch rose and fell at differing rates during the earthquake. Finally, I will overview the current thinking in New Zealand on where and how to rebuild Christchurch.