An extraordinary image

This picture was taken from the Gondola on the Port Hills, the moment the quake struck. The map shows the distribution of earthquakes between September 4 2010 and February 22 2011.

The latter quake was associated with energy release at the eastern end of the fault. The proximity of the epicentre to the Christchurch CBD was the main reason for the destruction.

For an excellent explanation from a GNS scientist see

http://www.youtube.com/watch?v=xuczXoFAgeI