The 2010–2011 Canterbury, New Zealand, seismic sequence: Multiple source analysis from InSAR data and modeling

The 2010–2011 Canterbury sequence is a complex system of seismic events that
started with a Mw 7.1 earthquake and continued with large aftershocks with dramatic
consequences, particularly for the city of Christchurch. We model the main earthquakes
using InSAR data, providing displacement maps and the respective modeling for the
September 4th, 2010, February 22nd, 2011 and June 13th, 2011 events. Relocated
aftershocks, field and GPS surveys are used to constrain models obtained by inversion of
InSAR data; the fault slip distribution is retrieved with a variable patch size approach
aimed at maximizing the spatial resolution on the fault plane. For the September 2010
earthquake we estimated significant slip values below 10 km depth; the calamitous
February 2011 event in Christchurch is modeled with a double fault source with slip values
less than 2 m down to 7 km depth; for the second June 13th event in Christchurch we
identified a NW-SE striking fault as responsible for the earthquake. Last, we introduce the
use of InSAR coherence maps to quickly detect the areas subject to soil liquefaction in
Christchurch, as shown for the two main events.