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When it comes to earthquakes, early warning systems are based on a simple principle: the shaking from an earthquake travels at about the speed of sound, meaning it would take more than a minute for, say, a 7.8 earthquake that starts at Salton Sea, to shake up Los Angeles 150 miles away.
Seismic sensors stationed at Salton Sea could detect the first shaking waves in as little as 5 seconds, and blast a warning throughout Southern California. In this scenario, Palm Springs would have 20 seconds of warning; San Bernardino, 45 seconds; and the Los Angeles area, more than a minute.
According to emergencymgmt, Louisiana-based Global Security Systems has designed a machine that would be like a weather radio for earthquakes, listening to warnings carried over a commercial FM radio frequency and then flashing a strobe light or sounding an alarm.
This firm already sells an Alert FM device that issues warnings for hurricanes and tornadoes. A home version costs about $35, while a $300 version could be installed in malls or offices and issue voice commands on what to do.
“We can have this deployed in California in less than nine months once the data is ready,” says Matthew Straeb, Global Security Systems’ executive vice president.
The city of San Francisco would like to eventually broadcast alerts to the public by phone and text message, and possibly on the 112 sirens throughout the city, which now go off only sparingly, like for tsunami warnings, said Francis Zamora of the city’s emergency management department.