According to the NZ Herald, March 7, 2011, a sizable portion of downtown Christchurch buildings that suffered major damage will not be rebuilt.
In a major departure from the usual recovery decisions after an earthquake, national officials in N.Z. have decided that “…parts of Christchurch will have to be abandoned and up to 10,000 homes could be demolished as a result of last month’s earthquake, Prime Minister John Key said today.” Earthquake Recovery Minister Gerry Brownlee previously told NZPA early estimates suggested 100,000 homes could need repairs while 10,000 could have to be rebuilt.
Prime Minister John Key confirmed those numbers this afternoon, and said the Government was working to identify which homes would have to be demolished.
There will be some homes that can not be rebuilt and, as a result of the second earthquake, potentially, some sections and some areas of Christchurch which will need to be abandoned,” Mr Key said. We will have to present 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 timeframe.
This is not a common outcome after an earthquake in a major urban area, but one that bears watching on the part of public officials in other seismically active areas. If any readers can supply related examples, I would be interested in hearing about them. I did hear from Prof. Rob Olshansky who offered some additional insights into what the land issues might be:
As I read it, it’s not that the land is so unsafe as to be unbuildable. Rather, the ground deformation requires additional preparation (e.g., geotechnical investigation, regrading, possibly drainage measures, possibly import of fill material, and redesign of foundation concepts), that they cannot rebuild quickly and that extra expense would be involved.
Later in the day some additional information about the effect of liquifaction on the damaged buildings in question –today’s The London Daily Mail.
Additional resources include those of the USGS regarding landslides and land failures: see: landslides.usgs.gov.