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Comment by anondon | Hacker News Reader

Does anyone know if there is any special effort to construct buildings that can withstand reasonable earthquakes in New Zealand?

Christchurch seems particularly prone to quakes in New Zealand. I hope the people of New Zealand are safe.

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Nearly 2/3rds of the casualties from the 2011 earthquake were a single building that contained an ESL school, a nursing school, and a clinic - and the construction supervisor of that building wasn't actually an engineer, but had stolen a retired engineer's identity.

https://en.wikipedia.org/wiki/CTV_Building

We have fairly comprehensive building regulations for all new housing. Our new house plans were rejected because we didn't specify strong enough straps to fix the hot water cylinder to the wall. The straps they insisted on would withstand 10 times the force experienced in the Christchurch earthquake, which was one of the most violent in terms of acceleration ever. When the big one happens, our house may be destroyed but by god the hot water cylinder will still be attached to the wall!

New Zealand in general is very quake-prone - our nickname in Victorian times was "the shaky isles". In fact our country owes it's existence to a particularly nasty intersection between the Australian and Pacific plates, with the Aussie plate slipping under the Pacific in the South Island, and vice versa in the North Island. You might think that the bit in the middle would be particularly dangerous, and you'd be right. Now guess where we built Wellington, our capital city?

Finally, there was a nice anecdote about some US hotel guests standing in the cold and dark after being evacuated from their damaged hotel. Asked if this had changed their mind about moving to NZ, they replied "Hell no, Trump is a far worse disaster than this!".

Yes, there are earthquake standards for new buildings, and mandatory retrofitting for older buildings (as they are updated).

From what I've seen, this is pretty similar to San Francisco. It would be interesting to see data comparing the standards across earthquake-prone countries/regions.

I used to work for a structural engineering company that had offices in both NZ and California, from what I understand the standards of earthquake engineering in NZ are higher than in California.

To be honest I think you're probably safer in a large earthquake in a post Christchurch NZ than in a small earthquake in a country that doesn't usually get them.

Christchurch is actually not on the fault line, and it was a surprise when such a severe earthquake hit in 2011, so they weren't well prepared. All the susceptible buildings collapsed then, and new buildings are earthquake-proof.

A big problem in the Christchurch region is liquefaction. There's not much earthquake codes can do to keep the ground from turning to goop.

It wasn't liquefaction that killed people though. That is what removed a large portion of the housing stock in the east, however.

You're completely right. Earthquake codes save lives, but in liquefaction zones, the structures may be unlivable afterwards even if they're completely intact.

The point of earthquake codes is not that the buildings are livable in afterwards, in fact in Christchurch something like 30% of all buildings had to be demolished. The point is that they stay up long enough for rescuers to get in, and if they do collapse they collapse with survival cells rather than pancake. In Christchurch the buildings performed very well with exception of the CTV building which pancaked. Although I know that a few buildings were only seconds away from collapsing so we were very lucky.

Don't forget the PGG building... and all the unsecured facades that collapsed onto streets killing people, a risk known about since the 90s.

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