Things sound pretty bad there, from the reports I’m reading. Usually these things hit in lesser-developed countries, and in the US, we could probably take a hit that big, at least in the west, with relatively few fatalities, because we’ve long had building codes for it, but it sounds like there was a lot of unreinforced masonry in the town, and the epicenter was very close.
But people on the east coast should be aware that it could be just as bad if one hits there, and while it happens a lot less often than in California, it can still happen.
[Update a couple minutes later]
Here’s an interesting animated map showing all of the temblors today, most of which were aftershocks, and big ones. It looks like it’s on the Greendale fault.
[Update a few minutes later]
Here’s all the coverage at the New Zealand Herald.
[Update about 10 PM PST]
CNN is reporting at least sixty five dead. I suspect the toll is going to be quite a bit higher when they clear the rubble.
Not the Greendale fault, that was the original 7.1 earthquake back in September. This last earthquake was under the Port Hills, within 10km of the central business district of Christchurch (the largest city within about a 1000km), and only 5km deep. Lyttelton harbor is an extinct volcano that excavated itself something like 10 million years ago, which might suggest something of the geology – volcanic rock, although Christchurch itself is on shingle.
New Zealand building codes take earthquakes quite seriously. The vast majority of residential homes are only one story and use light timber construction, partly for this reason, and there have been few casualties in the residential areas closer to the epicenter than the CBD. I would also note that the previous 7.1 earthquake resulted in no fatalities though it was something like 40km away from the center of Christchurch and 10km deep. The problem has been the taller older buildings, particularly stone buildings and brick facades, although this time round a few of the more modern taller buildings have suffered, and this is where most of the casualties are. In a town 80km south no significant infrastructural damage has been reported, let alone casualties. This earthquake was also in the middle of the day, if it had been at night like the previous one, there would have been few casualties. But I think the major point is that proximity to the epicenter matters, and this one was very close to the middle of town, and very shallow.
If this earthquake had occurred within 10km of the center of LA or SF, I suspect casualties would have been much higher. I would not assume that California would have faired any better.
Quite shocking to see photos of piles of rubble in places you remember walking/standing.
The Newport-Inglewood Fault (which runs just a couple miles from my house) is easily capable of a 6.3, and would be about the worst expected for the Los Angeles Basin (it was the one that caused the Long Beach quake in the thirties). We’re theoretically designed for it, but I wouldn’t want to be on a high overpass when it happened. The “Big One” on the San Andreas would actually not be as bad for LA, because its closest approach is about sixty miles from downtown.
Yeah terrible. [switches over to Seinfeld]
Christchurch has about half the population of the city of San Francisco, but it is much more spread out (lower population density) and the houses are generally single story and on a quarter acre section. I think this helped a lot. Although brick chimneys do seem to have been a bad idea, many came down in the first earthquake almost killing people asleep beneath.
Looking back at the 89 Bay Area earthquake (6.9, 18km deep), the epicenter of which was near Santa Cruz. Most of the fatalities were in Oakland (around a 100km away), not Santa Cruz. It seems magnitude and proximity are not necessarily a direct indication of likely damage. This last 6.3 earthquake in Christchurch has caused far more damage then the 7.1 earthquake back in September that resulted in no casualties, even though there were towns and farm houses directly above the epicenter and the epicenter was only 40km away from the center of Christchurch.
Heavy buildings around 3 or 4 stories seem to have caused the majority of casualties in this last earthquake. This seems to be where the building codes have been weakest. Natural frequency may also have something to do with it (this can be far more destructive for shorter buildings).
“We’re theoretically designed for it, but I wouldn’t want to be on a high overpass when it happened.”
After the 1989 Loma Prieta quake, where sections of double-deck freeway collapsed and squashed cars underneath, I was always more afraid of being *under* a very high overpass. Especially after they pulled a survivor out of his crushed car after a week (only to have him die in the hospital). A long fall always seemed preferable to that…
My wife and I visited Christchurch in December, 2009. Beautiful city, nice aviation museum, nice people. We even discussed retiring there.
Every time I drive under the south runways at LAX I think, “I hope there’s not a quake right now…”
That’s funny because the first time I ever drove south down Sepulveda and saw a 737 pass low through the office towers, I thought, “I hope there’s an airport down there.”
Yeah terrible. [switches over to Seinfeld]
That was an incredibly thoughtless thing to post. I hope you never have to bury your child.
I found the aftershocks (shown on the animated map) to be interesting. This shows once again that if you’re in a big quake expect a lot of aftershocks. In this case, one aftershock was almost half as powerful as the original quake.
I found the aftershocks (shown on the animated map) to be interesting. This shows once again that if you’re in a big quake expect a lot of aftershocks. In this case, one aftershock was almost half as powerful as the original quake.
The suggestion is that you should expect something like one aftershock of one order less magnitude, 10 of 2 orders of magnitude less, and a 100 of 3 orders of magnitude less. The aftershocks from the first earthquake went on for months and were really starting to get to some structures and some people.
I agree, I can’t imagine why one would even take the time to post that.
I mean, if you care so little about widespread death and destruction, Trent, then why even bother taking the time to make such an insensitive post? That is, unless you just like to periodically demonstrate how big an asshole you are. In which case, BRAVO! You’ve met your quota for the day.
Unfortunately the very thing that gave Christchurch its charm, Victorian era brick and masonry construction on an alluvial plain seems to have been its undoing. My general impression growing up in NZ was that ChCh was not considered a high risk area in earthquake terms. As a result there seems to have been less retro-fitting of old buildings than might have been ideal.
Given the very real risks posed by earthquakes in NZ the authorities seem to have been somewhat less well prepared to deal with the experience than is desireable. I am hopeful that the Christchurch experience will shake up (pardon the pun) the civil defense organization enough that the response to the next big quake will be more effective.
To get an idea of the true horror that is possible in NZ look at the situation in Wellington (the capital) where the entire city is built along the boundary of the Pacific Plate, much of it on land reclaimed from the harbor. There is only a single major road in or out of the city, which will be destroyed in any major earthquake and the airport, as anyone who has ever flown in or out of the city knows, is marginal even before it has been damaged. The last major Wellington quakes were in the 1840s and 50s, very soon after the beginning of European settlement.
Yes Wellington is a big worry, and due for a big one. Christchurch is rather surprising considering how far it is from the Pacific plate boundary (ring of fire) that goes down the center of the country.
So much for the planned South island trip starting Friday. Booked to fly into Christchurch. Emails not getting through to car rental company. My wife’s NZ siblings are recommending a North Island trip instead.
I’ve lived through one earthquake. The Meckering, Western Australia one in 1968. A bunch of us were in the library 5 floors up in the Physics building at the university of Western Australia. Brick building. Took around a few microseconds to figure this out and head for the stairs. We were outside in less than 30 seconds.
For the last few months Australian tv has been reduced to live coverage of the current ongoing disaster.. with the local news hound talking into the camera and providing no new information for hours on end. First we had the floods, then we had the storms, now we have the earthquakes in our neighbour across the ditch. So you’ll excuse me if I’ve had enough of the blatant ratings grabbing morbidity.
My flight left Christchurch at 11:35. The quake hit about the time I landed in Auckland.
Don’t be a wanker, Trent.
I am now wondering what the protocols are for an aircraft accelerating for takeoff when the runway starts moving.
I am now wondering what the protocols are for an aircraft accelerating for takeoff when the runway starts moving.
It’s probably stop if you have the room else takeoff. An aircraft which is parked on the runway might get seriously damaged from rocking, but that’s not likely to kill anyone.