Wednesday, November 24, 2010

New Zealand Earthquake Equivalent to M7.8 in Low Frequency Seismic


 "We've known for quite a long time that there's stirrings under a placid surface," she said.

I think this will go down as the most complex rupture of all times.  This is what I've always said, and this is what they are saying now.  Although M7.8 in low frequency (non-damaging) it was only an M6.0 (Parkfield) in generating damaging Peak Ground Velocity (PGV).  As they say here, this had to come from a spaghetti mess of fractures.  I wish they would have had borehole accelerometers.

In comparison, many M7's are 'clean', in that they are a simple rupture of a smooth fault.  As mentioned in my popular 'Kobe Earthquake' article, this can produce horrendously high PGV's that will knock anything down.

The earthquakes that we can expect around my neck of the woods will be 'clean punchers'.  They are characterized by a relatively flat b-curve, which means not a lot of warning.

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