Wednesday, October 24, 2012

Costa Rica earthquake - interesting high frequencies


I find the whole Caribbean mini-plate interesting.  Is it on the move?  Can a small plate act as a rigid body?  We don't understand anything about the forces on plates - ridge push, slab pull, or under-currents.

This earthquake was interesting in that it was relatively shallow, and produced no significant PGV.  However, it did produce a heck of a lot of noise.  Had there been accelerometers on rock, we would have seen record-breaking peak accelerations, which are somehow important to engineers, but totally meaningless because of the high frequencies.

As such, this earthquake resembles something we would expect in our neck of the woods.  Note that they must not have any jiggly swamps, or that buildings on them were destroyed long ago.  We, on the other hand, put all our buildings on Christchurch-like swamps, and will suffer accordingly.

No comments: