The Cutting Edge: Computing / Technology / Innovation : An Earthquake Alert System
Most people can tell when an earthquake hits, but some need to know the epicenter and the magnitude a lot more precisely than others. More than 100 Southern Californians--mainly utility and emergency services workers--carry special pagers that are activated by the Caltech-U.S. Geological Survey Broadcast of Earthquakes system two minutes after a magnitude 3.0 or greater earthquake.
From Quake to Belt 1. Earth movements are detected by a network of seismometers and transmitted by microwave or phone line to Caltech computers. 2. The computers quickly determine the location and magnitude of the earthquake and place a call over a special radio link to AirTouch Paging. 3. AirTouch relays the CalTech data by satellite to its switching stations in Atlanta and Chicago, which immediately send it back to Southland transmitter sites.
4. The local transmitters echo the message to subscribers with the special earthquake pagers.
5. Pagers displays the time, date, magnitude and epicenter of the quake.
Sources: Steve Bryant, CalTech; Bill Frank, AirTouch Paging
Researched by ADAM S. BAUMAN / Los Angeles Times
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