“A city destroyed”

Today the BBC called Christchurch “a city destroyed.” A report from the city opens with footage of buildings continuing to crumble as people run panicked in the streets. The count is 65 dead so far, with many more still trapped under rubble. The clock is ticking.

It’s a far cry from the result of a much bigger earthquake last September. Yesterday’s quake was magnitude 6.3; the one last year was 7.0. The older quake had seven times more shaking power, yet there was very little property damage and no deaths. Why was yesterday so different?

This is why:

two quakes

I plugged the coordinates of the two quakes into Google Earth, and then took some measurements. Last September’s much stronger quake was centered 65 km (40 miles) from the center of Christchurch. Yesterday’s, however, was just 9.5 km (6 miles) away from the city center. To make matters worse, it was only 5 km (3 miles) deep.

Unless the fault line ran directly beneath City Hall, you really can’t get much closer than that. This may have been a much smaller earthquake in terms of magnitude, but because it was so close to a major population center, the perceived shaking and physical consequences were huge. On top of that, last year’s quake probably stressed the buildings of Christchurch in ways that could not be seen. That made them more vulnerable to yesterday’s much, much closer earthquake. It’s not a surprise that so many of them crumbled.

I know there are several readers of this blog who live in New Zealand. I fervently hope they, and their loved ones, are safe today.


About Fletcher DeLancey

Socialist heathen and Mac-using author of the Chronicles of Alsea, who enjoys pondering science, politics, well-honed satire (though sarcastic humor can work, too) and all things geeky.
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7 Responses to “A city destroyed”

  1. Cheryl & Danae says:

    We’re from Christchurch. Dont know if we will ever sleep again – Mother Nature has just reminded us again that we are simply visiting, at her pleasure. Absolutely surreal.
    Times like this do bring us closer together, a shame it takes a catastrophe like this. Thanks for all the good thoughts.

    • oregon expat says:

      I am so glad to hear you’re safe. And I understand about not sleeping! We had a 5.6 earthquake off the southern Portugal coast a year ago, just enough to really shake the building, and even now my wife and I still freeze in place every now and then as our minds play tricks on us. For a few seconds, we’ll swear we can feel the building shaking again. I can only imagine what your minds are doing to you right now…and will for some time to come. We are deeply wired to respect those messages from Mother Nature, even when they aren’t as drastic as yours was.

      Stay safe, and expect aftershocks.

  2. I was horrified to learn of this quake. Not having cable, or a television, I was online when I found it and watched news footage in absolute horror. My thoughts with the people there.

  3. Kugai says:

    It’s been a shocker of a day down in Christchurch alright. I was worried about a mite of mine who was due to head down there to work on the reconstruction from Septembers quake, but I found out that, fortunately, he was still up here in Wellington.

    He’s worried about his mates already down there, but I was glad to hear that he was OK.

  4. xenatuba says:

    I had read your post just before going to bed; as is my custom, I turned on the Weather Channel while I was getting ready. Lo and behold, there was their correspondant saying exactly what you said above.

    A friend of mine from Michigan was in the SF bay area for one of their recent quakes (Loma Perita, I believe, in 1989). She was driving on 280 and thought she was “tripping out”. Her next thought was that all of the other drivers were being influenced by her. Quakes are scary things.

    • oregon expat says:

      They are very scary things, and feed right into a deep, deep well of fear in the primitive parts of our brains. That said, I must admit having a chuckle at your story, because how appropriate is it that a San Francisco resident would think she was tripping out during an earthquake? I’m envisioning a San Francisco couple in their apartment: “It’s an earthquake! Get under the table!” “No, dude, it’s all right, it’s just an LSD flashback…”

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