Thursday, June 6, 2013

Super-shear earthquakes


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.


Anonymous said...

How would all those highrise condos in TO do under this earthquake scenario?

Harold Asmis said...

The condos are pure crap. I watch them being built. All those thin walls, and all glass. I shudder.

Anonymous said...

Will they come down or just shower glass on pedestrians. If they remain standing, are they still structurally sound?

Harold Asmis said...

They will still stand for escape, but will have to be torn down, much like Chile.

Anonymous said...


I can't begin to imagine the insurance claim!!!