Friday, March 23, 2012
Fine Australian earthquake
Absolutely in the middle! Why does Australia have these earthquakes? No water, no people. And if somebody eventually visits it, they will find it cracked the surface. This is a case of high horizontal stresses without glaciation. The continent has been shoved around, and is in a nice cool spot. It settles and crunches the crust. We would be exactly the same in ENA but we had glaciers acting as giant hammers, pounding the rock to crumbles. Thus, most things that would fail in a few thousand years have failed already.
These hard-rock events generate almost no PGV to speak of, but a very high PGA. Of course, if you are right on top, it'll throw you!