Christchurch was at lunch. It was 12:51 p.m. on Tuesday, February 22, 2011 — office workers at their desks or out on the street, students in classrooms, shoppers in the city centre — when a shallow earthquake struck almost directly beneath the city. The U.S. Geological Survey lists it as magnitude 6.1; other catalogues put it at 6.2, and New Zealand's local magnitude was 6.3. Its centre was in the Port Hills, less than 7 kilometres southeast of the central business district, at a depth of only about 5 kilometres.
In well under a minute, 185 people were dead or dying — New Zealand's deadliest earthquake in 80 years, since the 1931 Hawke's Bay earthquake (USGS). Thousands were injured: an estimated 6,600 to 6,800 people were treated for minor injuries alone. More than 100,000 buildings across the region were damaged or destroyed (USGS). A moderate earthquake by the numbers had produced a national disaster — because of where it struck, how shallow it was, and what it found waiting on the surface.
Christchurch had been shaking for months. On September 4, 2010, a magnitude 7.1 earthquake near Darfield, about 40 kilometres west of the city, had cracked buildings and chimneys across Canterbury — but killed no one, striking a rural area before dawn on a Saturday. The February quake belonged to that earthquake's aftershock sequence (USGS), rupturing a previously unmapped fault along the northern edge of the Port Hills.
That is the cruel arithmetic of earthquakes: the February event was the smaller one. But it was far closer to the city, far shallower, and it arrived at lunchtime on a working Tuesday, under streets full of people and buildings already weakened by five months of aftershocks. Seismologists call it a lesson in exposure. Christchurch calls it February 22.
The shaking was violent and strongly vertical. In the city centre, the six-storey Canterbury Television (CTV) building collapsed and caught fire. Of the 185 people who died that day, 115 died in that one building — many of them international students at a language school inside, among victims from more than 20 countries. Eighteen more people died in the collapse of the Pyne Gould Corporation building. On Colombo Street, falling masonry crushed a passing bus, killing eight.
The spire of ChristChurch Cathedral — the city's symbol — snapped and fell into Cathedral Square. Across the centre, unreinforced masonry façades dropped onto footpaths and streets. Both the CTV and PGC buildings had been damaged in the September 2010 earthquake, then inspected and re-occupied afterwards — a fact that would dominate the inquiries to come.
Away from the centre, the earth itself failed. In the eastern suburbs, built on soft river sediments, liquefaction turned streets and gardens into erupting silt and water; homes sank, tilted and flooded. University students, organised as the Student Volunteer Army, shovelled away an estimated 360,000 tonnes of liquefaction silt in the weeks that followed. In the Port Hills suburbs of Sumner and Redcliffs, cliffs collapsed in rockfalls that added to the toll and closed roads.
New Zealand declared a state of national emergency, which stayed in force until April 30, 2011. Rescue teams worked the rubble for more than a week; the last survivor was pulled out the day after the quake. The Canterbury Earthquakes Royal Commission, established that April, spent more than a year examining why buildings failed. Its verdict on the CTV building was damning: the design contained fundamental errors and did not comply with the building standards of its own day — it should never have been approved. The PGC building, designed in the 1960s, was earthquake-prone by modern standards. As with İzmit in 1999, the disaster was less an act of geology than a verdict on construction and inspection.
Much of the central city was eventually demolished and rebuilt. Thousands of homes on liquefaction-prone land were bought out and their neighbourhoods left empty — the residential red zone. Post-earthquake building assessment became stricter and more cautious nationwide. And for seismologists everywhere, Christchurch became the standing warning the USGS identified at the time: the hazard posed by fault lines, both mapped and unknown, near major cities. The fault that broke Christchurch had not been on the maps. Many cities are built above others just like it.
Read what to do before an earthquake, during, and after.