You always need to act on it. Get an earthquake alert? Run outside. You can go back if it was a false alert.
In Mexico City the seismic alert gives like a minute (sensors are on the coast off Guerrero 350km away). Communities closer to the usual epicenter get almost no warning.
In Mexico City the seismic alert gives like a minute (sensors are on the coast off Guerrero 350km away). Communities closer to the usual epicenter get almost no warning.