Quake-hit areas to be abandoned
New Zealand's prime minister has said around 10,000 houses in Christchurch will have to be demolished because of earthquake damage and some parts of the city abandoned altogether.
The magnitude-6.3 earthquake that struck on February 22 shattered homes, heritage buildings and office blocks.
Officials said the confirmed death toll is 166 and is expected to rise to more than 200.
Prime minister John Key said "there are some parts of Christchurch that can't be rebuilt on" because of liquefaction and other land damage.
Liquefaction can occur when earthquakes cause sections of earth to liquefy and push up to the surface as watery silt. In Christchurch, 260,000 tons of silt have already been scraped away.
"The liquefaction damage from the ... earthquake is so great and the land damage ... is so significant we can't remediate it," Mr Key said.
Mr Key said around 10,000 houses would have to be demolished in the city, including 3,300 damaged by an earlier magnitude-7.1 quake on September 4. That quake was deeper and further away than the February 22 event and did not cause any deaths or as much damage.
Several hundred central city commercial buildings will also have to be bulldozed, Mr Key said.
"Potentially there are some ... areas of Christchurch which will need to be abandoned and we will have to provide other alternatives for people to live in because the land has been so badly damaged, we can't fix it - certainly not in a reasonable time frame," he said.
A national memorial service is planned for March 18 and Mr Key said the open-air event in a city park could attract up to 100,000 people.