Michael,

I think far more people hear ear tones but think their ears are ringing and never make the connection to earthquakes.

The time for most quakes is within ten days, but for us in the Bay Area quakes for Southern CA and south often take longer, usually in the 15 day range. North often arrive faster. The problem is that quakes can arrive in as little as 45 minutes which doesn't allow much time for a warning to anyone.

None of us have ever heard a tone at the same time. We may get them at different times on the same day, but most of the time the reports come on different days. The Off-Shore Oregon quakes picked up by four of us all came on different dates and different times of the day. That means that there are more times when these sounds go out than just once in most cases. The one thing about them which is curious is that when they are heard it gives you such a sense of something happening immediately and that is rare. But it explains why animals run away. They act on what they hear and we humans wait.

I hope you'll keep a log of your tones and look for matching quakes. If you find you are keenly interested, you're welcome to participate in my research group.

Petra