Hi Randall. I have a suspicion that this may be occurring more then we think, or really know. There has been two occasions where this has occurred in the San Juan Bautista area and is almost an on going occurrence in the Parkfield area that started around 1993. It will stop then start up again with no quakes associated with it. There was one time it was seen at Parkfield and San Juan Bautista at almost the same time. To date nothing has ever occurred because of that. A major quake could occur in the area 5 years from now, but there is no way of knowing if this was a precursor to that quake or not.

It has been occurring for 2 years now in the area of the expected Tokai quake in Japan. At present time they have no idea as to what it means in that the subduction fault that it is occurring on is still being subducted on both sides of it.

This old earth we live on still have a lot tricks and mysteries that we haven't seen yet and may never really understand them when we do. Take Care…Don in creepy town