Sunday, April 17, 2016

Ecuador earthquake - Year of living dangerously


The tabloids are all screaming that we have a 'pattern' of world earthquakes, and that we are due for a 'big' one.  This M7.8 is pretty big, but not really that big for a subduction earthquake.

Looks like it ruptured the smooth curve.  You can see how clean and crisp the zone is, and I have found this means a big earthquake every few hundred years, usually a 9 or more.

The whole zone is not that smooth, so a 9 would have trouble rupturing a length 10 times longer than this one, but it must happen for sufficient displacement to keep things clean.  You can see that the rupture here is fairly short, no tsunami, and they probably can't measure the displacement.

The fault plane solution is a classic subduction zone.  Firm ground PGV is probably 10 cm/s but the intensities look like soft ground amplification.  The coast seems pretty isolated.

Remember, there is no 'pattern' here.  We are not entering a phase of big earthquakes.  We just tend to see clusters once in a while.

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