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Another Strong Earthquake

April 12th, 2011

Woke up about 15 minutes ago to another strong quake. Not the 7.0 of last night in Fukushima, but to a 6.3 in Chiba, just 80 miles (130 km) to our east.

I’m beginning to wonder… this many strong quakes a month after the primary… is that normal?

  1. Troy
    April 12th, 2011 at 11:56 | #1

    9.0s don’t mess around.

    You’re now 8′ closer to Korea than before. More tectonic adjustments wouldn’t be surprising. . .

  2. Roger
    April 13th, 2011 at 11:02 | #2

    A thought I had… perhaps it is normal to have kind of a logarithmic distribution… where whatever the size of the main quake you end up with a handful of aftershocks one magnitude level lower and maybe a couple score of aftershocks two magnitude levels lower, and hundreds three magnitude levels lower, etc. Thing is we don’t usually notice or care about a 4.0 aftershock after a 6.0 quake (and certainly not a 3.0)… on the other hand, a 7.0 aftershock is significant – even if it’s still a couple orders of magnitude smaller than a 9.0. Just an idea. But then, as Troy notes, 9.0s don’t mess around. Which seems like an equally valid hypothesis on the face of it.

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