Hi Petra,

Thanks for the information. I'd tried doing a search off the main page, but no engine was available. You really helped me by clearing up the difference between ringing and tones; now I know what to look for if I ever experience them.

I really like your idea about miking the earth. Any signals that can be captured should be studied to see how they relate to earth movements.

Good luck in your research!

Bye for now, and thanks again, Billion