The Atavism

Wednesday, February 23, 2011

A clearinghouse for #eqnz science reports

Like many New Zelanders, I'm struggling to understand what happened yesterday. We all know that a devestating earthquake struck Christchurch around lunchtime yesterday, killing at least 75 people and destroying much of that beautiful city. Of course, the tragedy of the Christchurch earthquake can be measured only in the lives it's affected, you don't need to know about rocks to understand this story, which has no doubt been repeated in a thousand different variations across the city. Obviously, the most important thing at the moment is that people in Christchurch get the help they need. Still, if you have a brain like mine, then somewhere in the struggle to understand the tragedy and the overwhelming feeling of uselessness you just need to know how this happened. I'm going to use this post to collate links to articles that do a good job of explaining some of the science behind yesterday's earthquake, but first here's what I've learned from reading them.

The quake seems to part of the sequence of aftershocks from the 7.1 Darfield earthquake of September. It might be that the massive release of pressure in that quake added to the strain at a fault that was already under stress; or it might simply by part of the pattern of aftershocks following that quake which have been progessively more shallow as they've proceeded. What's abundantly clear is that, even though this new quake was 6.3M and therefore about 5 times less intense than the Darfield one at its origin, it was much more violent than the first. The eipcentre was only 5km for the centre of the city and only 5km below the surface. The peak acceleration, one measure of the strength of the shaking from a quake was 1.88 g which is about 50% stronger than any measurement from the Darfield quake and much greater than anything recorded near to the city in that event. That powerful shaking, the lunchtime rush and already damaged buildings proved to be a terrible combination.


Science Media Centre



General Aggregators

I'll keep this post updated with any new pages that add something to the story, so please pass any useful links along in comments or via email (david.winter at gmail).

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    Posted by David Winter 4:44 PM


    Thank you for this! After the dreadful experience of yesterday I was quite desperate to hear the science and found myself quite tearful once the seismologists and geologists started appearing on the television and explaining what was going on. There's so much woo in the air when disaster strikes and I relish the comfort of empirical explanation more than ever.

    (My family is fortunate both to have survived and have no further damage to our homes. We feel tremendously fortunate.)
    Thanks Hbird,

    I was very happy to see you and the whanau check-in on twitter.

    Glad you like this. I worried a little about whether I should put it up at all, lest it seem like focusing of the wrong part of a terrible story, be reasoned there would be other people like me struggling in the same way I was.
    Hi David,

    Thanks for this. I found it much more useful than the Australian. Chris Rowan's site was especially informative.

    I suppose there is a danger of dwelling too much on the science as a way of not dealing with the human tragedy. But people are living in New Zealand, and Japan, and the West Coast of North America (where I once lived), and many other places where there will be earthquakes and tragedy in the future. Good science can't save them from that, but it can help to save lives and reduce damage. Perhaps more importantly, a scientific understanding is a good antidote to feelings of guilt, depression, and hubris.

    Before science, earthquakes would have been blamed on gods or witches or the evils of man. It was good to see and read scientists trying to explain this disaster to the limits of their knowledge with no obvious political motives or pretense that their models could predict the future.
    Thanks Dave,

    We actually have an "astrological forecaster" in NZ who claims to have predicted this one - so I think you can add insanity to hubris, guilt depression and hubris ;-).

    I think Chris Rowan and Mark Quigley in particular have done a very good job of explaining what's going on.
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