I think sensors can now give up to about a minute's notice. Which would be enough to stop trains and evacuate certain buildings.
Not much time except maybe to run outside or brace inside a doorway. I was thinking that someone should invent a device sort of like the President had in "Escape from New York"- like a pod you could have in your house that would be strong and fire-proof, like a gun safe, and padded inside- or even some kind of expanding foam if detect elevation change- to cushion a person in an earthquake or tornado. It would have some compress 02 and would have a way for the person to escape from the inside (unlike a safe) and could also have a small survival bag with immediate necessities: first aid, some cash, a pistol, basic medicine, bandages, compass, matches, knife, signally mirror, emergency foil blankets, small water purifier/filter, paracord, map, collapsible water jug, etc.)