September 2010 Earthquake
The Darfield earthquake was a 7.1 magnitude earthquake which struck Canterbury at 4.35am on the 4th of September 2010. The epicentre was 40kms west of Christchurch, near the town of Darfield, at a depth of 10km. The earthquake lasted around 40 seconds and was felt widely across the South Island and also in the North Island. No tsunami occurred because the epicentre was inland and, therefore, caused no shifting of the sea floor. This earthquake was a result of a strike-slip fault in the crust of the Pacific Plate near the Southern Alps, west of the Canterbury Plains. Even though the earthquake occurred in a fault away from the Australian/Pacific plate boundary, it was related to movement of these plates causing stress to be absorbed through a number of faults in the region.
February 2011 Earthquake
The Christchurch earthquake was a 6.3 magnitude earthquake which occurred at 12:51pm on the 22nd of February 2011. The epicentre was 10kms south-east of the city centre and was 5kms deep. Seismologists consider this earthquake to be an aftershock occurring nearly six months after the September 2010 earthquake as it was one of a long series of earthquakes of lesser magnitude than the larger initial earthquake.