Pete, you might be interested in this AP clip by an AP correspondent if you haven't seen it already. Although I have worked in Japan, I didn't realize that they have an earthquake early warning system so maybe it's new. The correspondent mentions that just before the shaking started, there was actually a warning on TV. But that was Tokyo. I doubt that the people in Sendai had any lead time at all from that same system. I forget if it was the P wave or the S wave of an earthquake that travels faster than the other. Anyway, the farther away you are form the epicenter, the more lead time.

Actually, I raised the topic of an earthquake early warning gadget a while ago on ETS, and most folks seemed to think it was ridiculous and wondered why anyone would buy one. Seemed to make perfect sense to me. In many earthquakes, even if you're awake, it often takes a while for someone to realize, "OK, yeah, this is an earthquake." If someone could potentially be saved from injury or death because they responded just a few seconds sooner--getting under a desk, getting away a heavy bookcase, etc.--then that seems totally worth it to me.