Don,

It may be that there are places in China where earthquakes are preceded by swarms of increasing intensity, providing the possibility of warning, but that is not generally true in the US.

Also, in China it may be that mild alarms are retrospectively remembered as more specific, serious, and effective warnings. There is some suspicion that the 1975 casualties were understated to overstate the success of that prediction.

On the flip side, accelerating seismicity is one of the few patterns that seems to precede major earthquakes, although its predictive power is still in question.

Not much of use has been transferred from Chinese earthquake research to the US so far, however.

John