Thursday, June 6, 2013

Super-shear earthquakes

Article

I've always gone on about this.  The peak ground velocity (PGV) gets very high on the surface.  It's enough to knock down almost anything.  It's the F5 tornado of earthquakes!  From my research, it needs at least an M7, but this ground motion saturates for anything larger.  It produces a total disaster if it is right under a city.

It happens with a steep thrust fault under high stress, and very smooth.  Thus the critical displacement (the displacement required to invoke dynamic friction) is near zero.  With this arrangement, the P wave (compression) is sufficient to start dynamic slip, and you have a 'shock wave' that has very high PGV.

In the remote chance that the Hamilton fault is fully activated as an M7, it would be this type of earthquake.


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