English: Canterbury hydrogeology. (A) Geological map of the Canterbury Plains and Banks Peninsula, showing Christchurch urban area, inland semi-confined and unconfined aquifers (yellow), coastal zone of confined aquifers (green), piezometric groundwater contours (5 m intervals above sea level), and epicenters of the Mw7.1 Darfield (4 Sept 2010) and the Mw6.2 Christchurch (22 Feb 2011) earthquakes. (B) Schematic block diagram of the aquifer system and groundwater flow regime (adapted from Weeber, 2008). (C) Potentiometric levels relative to ground surface, highlighting the west-east difference in head between the shallow water table compared with deeper aquifer groundwater. Note that colour figures are available in the electronic version of this paper. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)