The California Earthquake Early Warning (CEEW) System has been in development over the last six years. It is composed of a collection of seismic monitoring sensors strategically located throughout the state, telecommunication pathways, including cellular, microwave, wireless and satellite, and alert distribution channels designed to detect the initial energy emitted from the hypocenter of an earthquake which is then translated into an alert that is sent out prior to severe shaking occurring at a location. This alert is called a "ShakeAlert".
The California Governor’s Office of Emergency Services (CalOES) is leading the effort to develop, fund, manage and operate the CEEW System. USGS, Caltech, UC Berkeley, the California Geological Survey and other universities and organizations provide the operational and scientific support for the system. The structure also includes research, public education and training, as well as finance and administration.
Earthquake Early Warning (EEW) systems use science, state-of-the-art monitoring technology, and innovative delivery methods to alert people via devices before the anticipated strongest shaking arrives in affected regions. Seconds to tens of seconds of alert can provide opportunity to take life-saving actions such as Drop, Cover, and Hold On and put devices into various forms of a safe mode.Individuals or businesses receiving an alert will vary depending on the distance they are from the epicenter of the earthquake. The closer you and individual or entity, the shorter the alert time; the further they are, the longer the alert time they will receive.
1. In an earthquake, a rupturing fault sends out three different types of waves. The fast-moving P-wave is first to arrive, but the damage is caused by the slower S-waves and surface waves.2. Sensors detect the P-wave and immediately transmit data to an earthquake alert center where the location and size of the quake are determined and updated as more data becomes available.3. A message from the alert center is immediately transmitted to users.
The earthquake early warning system in California will be able to provide seconds to tens of seconds of alert prior to strong shaking. People may receive a ShakeAlert before, during, or after shaking arrives at their locations. The length of time warning given to any location, before, or after shaking begins depends on a number of factors, including: