During disasters, radio and television stations are required to broadcast alerts. In the Bay Area these are:

Local Primary Radio Stations
KCBS AM 740 KQED FM 88.5
KSJO FM 92.3 KZST FM 100.1

All FM radio stations and all TV stations are required to carry every alert. Many AM stations carry them also.

The Emergency Alert System is a national public warning system that requires TV and radio broadcasters, cable television systems, wireless cable systems, satellite digital audio radio service providers, direct broadcast satellite service providers and wireline video service providers to offer to the President the communications capability to address the American public during a national emergency. The system also may be used by state and local authorities to deliver important emergency information such as AMBER (missing children) alerts and emergency weather information targeted to a specific area.