Monday, December 31, 2012
Slab on the move - Alaska M4.1 earthquake
This is as exciting for me as the Arkansas sequence! It is obvious that the slab is on the move, but at a very slow pace, and it may stop at any time. So don't waste your panic juice!
With the slab moving down, it was inevitable that the upper crust would see compression. This last earthquake is too small to get a focal plane solution, but it is shallow, and I imagine it would show compression. If things keep moving, we'll see more earthquakes here, and soon the Denali fault (terminal shear) will start singing.
As I have said before, no real earthquake has followed such an overture (just watched the new Lawrence of Arabia bluray).
Update: Further discussion in the Geoscience community of g+.