I disagree, in Japan we just had the "megaquake" warning for a week, maybe it was prudent but it was also very distracting, kind of worrying, and nothing happened in the end. On the other hand we have Typhoon warnings, which are actually much more predictable and quite useful.

My point, unless it's something like 90-95% accurate, I don't think it's useful at all. Mostly a distraction. When you live in a seismically active area, you just need to be prepared all the time.