petra...I, and almost everyone I have asked, hear ear tones. But, they have nothing to do with earthquakes at the distances expected by your equation...because here in suburbia, we have not been having any quakes. And, I can detect no link to large distant quakes. So, if it is working for you, then you must be hearing something different than me...

Your river analogy remind me of a cartoon...there are a couple of canoers at the bottom of a creek that has a sign "S### creek". One says, I don't think we should go up there, especially without a paddle.
Chris