Sunday, February 23, 2014

Oklahoma earthquakes bounce back to shear

If I had any energy, I would really do this in 3d.  There is shearing now along the NE zone, but it is along a gently dipping megathrust, so there will be some spread in earthquakes.  The thrust (formerly a transform fault) is nearly vertical.  Those earthquakes should be a lot tighter on the line.  They will also be much louder and have a higher PGV for their magnitude.  I am pretty sure there are no strong-motion instruments here.

We had massive activity on a very tiny portion of the thrust, and this was reported as 'explosions'.  I doubt these new ones along the shear were as loud.  I was expecting a larger thrust, but I think they are really downgrading them.  I now expect larger shear (strike-slip) quakes.  It would be going according to plan if the next shear quake were larger than the previous one (M4.5).  That one did not produce any significant shaking, and I don't expect the next one will either.  Then we go back to thrusts.

The next thrust will really knock people out of their socks, with a high-frequency pulse, but the seismologists will downgrade it significantly.  That's okay, because I don't want anybody to think this is serious yet.  :)

Update:  Quite a few more, looks like a good run.

up2:  M3 thrust down on the lower line.  Hope there are some felt reports.

up3:  Now we get a few days of rest.  I swear that this is the laziest mechanism I've ever seen!  :)

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