View Full Version : Christchurch earthquake...
02-25-2011, 04:48 AM
Well, I live in Dunedin, the next major city south of Christchurch, and as most of you PROBABLY have read, Christchurch was massively damaged by a big earthquake recently.
Any other Kiwi's here?
Anyone else like to comment?
I note that rescue teams from all over the world have helped us with this: America, Japan, Australia, Singapore, England...
Fantastic and warming inside to think of the support we have received from all over the globe...
02-25-2011, 11:05 AM
Not a Kiwi but I certainly know the pain and loss that arises due to being in the SF area in 1989 with a bit larger quake.
Strict building codes here do help stop people from being killed by falling buildings, one thing California government does do right.
(I immediately noted the un-reinforced brick construction in many of the Christchurch news photos.)
02-25-2011, 06:38 PM
Yes, many of those buildings are older, and were built long before modern building codes(which NZ does apply to new buildings), so they tended to crumple. This includes most 60's and 70's style brick houses, as there is nothing to stop the bricks on these houses falling down when shaken hard enough. As I understand it, modern brick houses do use reinforcing to help stop that from happening.
What concerns me most, is the Pine Guild Guinness building, which was four stories high I think, which pancaked trapping and killing many.
I was of the understanding that this building is not THAT old, so many here are asking why that one failed so completely - it should have been built to a standard which was modern enough that it should have stood. Many other higher buildings survived, although they too are badly damaged - but they did not collapse totally like the PGG building.
The CTV building is another total collapse, but I don't know how old that building is.
02-25-2011, 10:20 PM
The rule of thumb here is any structure within 1/8 mile of a breaking fault in a large quake is at risk to be destroyed or severely damaged. That is why hospitals and schools are no longer placed on fault lines here, and many hospitals that were built on the fault lines have been closed.
Bolting a house sill to the foundation won't help if the forces are large enough, 0.6 PGA is about the limit for wooden structures.
The latest techniques for large buildings in these areas include large rubber pads to allow the building to move on the ground vs shearing the structure laterally.
During one quake in Southern California the vertical forces were in excess of 1G, meaning buildings could literally be lifted off their foundations and slammed back down again.
Engineers can build stronger buildings but nature is the most severe tester.
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