Hi Michael and Petra,

I visit the earthquake tracker site frequently thanks to prior info about it from earthwaves. However, the article I referred to in my initial post stated that no indication of strain was given prior to the Loma Prieta event Petra. The only warning appeared to be from an ultralow-frequency radio receiver, picking up noise in the .01-10hz range up to 12 days in advance of the quake.

I don't know how much research has been done in this area Michael. It sure seems worthy of study. I've been looking for information, and found a that the ULF Group in the Department of Electrical Engineering at Stanford University performed measurements of ultra-low frequency (.01 to 10 Hz) magnetic fields. At one time they were operating six field stations at various locations around California. Still trying to find out more.

All the best, Billion