A major earthquake occurred in Christchurch on Tuesday 22 February 2011 at 12:51 p.m. local time (23:51 UTC, 21 February). The Mw6.2 (ML6.3) earthquake struck the Canterbury Region in the South Island, centred 6.7 kilometres (4.2 mi) south-east of the central business district. It caused widespread damage across Christchurch, killing 185 people in New Zealand's fifth-deadliest disaster. Scientists classified it as an intraplate earthquake and a potential aftershock of the September 2010 Canterbury earthquake.
Christchurch's central city and eastern suburbs were badly affected, with damage to buildings and infrastructure already weakened by the 2010 Canterbury earthquake and its aftershocks. Significant liquefaction affected the eastern suburbs, producing around 400,000 tonnes of silt. The earthquake was felt across the South Island and parts of the lower and central North Island. While the initial quake only lasted for approximately 10 seconds, the damage was severe because of the location and shallowness of the earthquake's focus in relation to Christchurch as well as previous quake damage. Subsequent population loss saw the Christchurch main urban area fall behind the Wellington equivalent, to decrease from second- to third-most populous area in New Zealand. Adjusted for inflation, the 2010–2011 Canterbury earthquakes caused over $52.2 billion in damage, making it New Zealand's costliest natural disaster and one of the most expensive disasters in history.
