Hi Don, Petra, and all:

I think I have heard about the slow EQs at Parkfield or Hollister, I don't recall which and I don't recall how I had heard about them. I had forgotten about them until you brought it up Petra. Thanks for ringing a bell! The magnetism ideas about EQs I am somewhat familiar with. I am curious about the shape of the magnetic field disturbance at a fault plane, as I have never heard anything about that subject with regards to EQs. I am familiar with the shape of the earths magnetic field, and wonder if a disturbance on a fault plane would be similar in shape or somehow different. Knowing something about that may help us to relate what signals we're seeing at Parkfield with relative strengths at the Diff Mags "stations".

It just seems obvious that magnetic disturbances would be an integral part of an EQ, not just an 8.0, but any size quake. A question I've always had about Parkfield is, being wired like it is, why hasn't anybody seen any signals preceeding small EQs? There's nothing different about a 2.0 that wouldn't apply to a 8.0, or so I think ;)

As you mentioned, small EQs/creep means the fault is moving. I assume that this comment only applies to the upper levels of the fault, correct? Do we know what is happening at depth? How deep is the SA at Parkfield?

Thanks for all the good info!

Michael