Speaking among the rubble hours after the minute-long shaking ended, the country's Prime Minister John Key said that it may well have been New Zealand's "darkest day."
He declared a national state of emergency to help agencies cope with the catastrophe.
Many of the fatalities occurred when the entire building housing Canterbury TV and a language school collapsed at the height of the business day.
One other large hotel building in the downtown area was heavily damaged and threatened to topple as strong aftershocks continued during the days after the 6.3 magnitude jolt.
The extent of the damage in Christchurch was due to the shallow depth and proximity of the epicenter, and because the silt and water beneath the city "liquified," increasing the force of the ground motion, seismologists said.
Initial estimates of the damage inflicted by the second quake to strike the Christchurch area in four and a half months were placed at $12 billion.
The shaking also caused a 30 million-ton iceburg to break off the Tasman Glacier and into a lake about 150 miles to the southwest of the epicenter.