22nd February 2011 - Christchurch Earthquake

23/02/2011

At 12.51 pm local time, Christchurch was once again struck by an earthquake. It has been classified as an aftershock to September's Canterbury earthquake although at 6.3 this earthquake was far more violent. This is due to an epicentre that was closer to Christchurch city and much shallower than September's quake.

Our staff are all safe. Our office is inoperable at the current time and we are in the process of retaining and setting up alternative work space.

Some of our staff are trained members of Urban Search and Rescue (USAR). Those members are on the ground in Christchurch and are assisting with rescue efforts.

Our Trevor Kelly has analysed the data from Geonet - some of the results are posted as an image right. The spectra recorded within 10 km of the epicentre show very large motions, much higher than code, for periods up to 2 seconds or longer.  This would cause very high response in low and mid-rise buildings. The black line on the chart represents the building codes for the area. This was an extraordinarily strong earthquake.