...In order to give sufficient warning, the shaking threshold for the alert has to be set very, very low. So, while earthquake early warning could very well save lives and reduce injuries, getting useful alerts comes at a steep cost—and that’s quite apart from money. Most alerts you receive will not be followed by strong shaking, and some shaking will be imperceptible. In these instances, the alert could be considered a nuisance. While the shaking threshold required to trigger an alert could be raised, doing so would increase the “blind zone,” the area in which no warning could be given. So, if you only want to be warned when there will be strong ground shaking (say, because scramming your factory is costly or disruptive), you will almost never be forewarned....