Earthquake Early Warning System

An Earthquake Early Warning System for the west coast of the United States is being developed by the United States Geological Survey in cooperation with scientists at academic institutions including: California Institute of Technology, University of California at Berkeley, and University of Washington. Under the Disaster Relief Act of 1974, popularly known as the Stafford Act(P.L. 92–288), the USGS has the Federal responsibility to issue alerts for earthquakes, to enhance public safety, and to reduce losses through effective forecasts and warnings. USGS currently issues rapid, automatic earthquake information via the Internet, email, text messages, and social media.

National Hazard Map

National seismic hazard map for the United States. Colors indicate peak horizontal ground acceleration (in % g) with a 10% probability of exceedance in 50 years. The earthquake early warning system is initially being developed in the western United States (California and Washington) where the seismic hazards are greatest and the density of seismic instruments approaches what is necessary to produce a useful warning.

Earthquake Early Warning (EEW) uses existing seismic networks to detect moderate to large earthquakes very rapidly so that a warning can be sent before destructive seismic waves arrive to locations outside the area where the earthquake begins. These warnings allow people to take protective action and can also triggering automatic responses to safeguard critical infrastructure.

Such actions might include:

  • allow people to drop, cover and hold on and grant businesses time to shut down and move workers to safe locations,
  • give medical professionals time to stop delicate procedures,
  • protect travelers by providing time for trains to slow or stop, for elevator doors to open, for bridge traffic to clear, for slowing or stopping traffic, and even stopping landings and take-offs at airports, and
  • enable emergency responders to prepare by opening fire station doors and starting generators.


Earthquake early warning can be used to slow and stop trains, alert and protect critical infrastructure, and provide a few seconds for people to take cover.