Our Earthquake Early Warning Detector For The Home
These devices work by detecting the faster traveling "P" waves that immediately precede the damaging earthquake "S" waves. The warning time works out to around 1-3 seconds for every 5 miles distance between you and the epicenter of the earthquake. For the Magnitude 8 earthquake risk we face here in Saint Louis, Missouri, that works out to 37 to 111 seconds of warning time. We'll have a follow up video to go into more details.
Below are Amazon links to the detector we use and other similar devices.