Earthquakes propagate very slowly (around 2-8 miles/sec). That's how systems like ShakeAlert can send out early warning notifications. This one, for example, ha

Earthquakes propagate very slowly (around 2-8 miles/sec). That's how systems like ShakeAlert can send out early warning notifications. This one, for example, happened 40+ miles from NYC proper, so residents could have had like 20 seconds notice if the service operated here. People further up or down the coast could have had multiple minutes.