The siren will alert the roughly 11,000 residents of the Tiburon and Belvedere areas to earthquakes, tsunamis, hazardous materials spills, fires, severe weather and other emergencies.
It is located at Tiburon Fire Station 11 at 1679 Tiburon Blvd., the fire district's headquarters downtown.
When residents hear the siren, they should tune their radios to 840 AM, the Belvedere Emergency Advisory Radio System, or BEARS, Tiburon Fire District Battalion Chief Mike Ayers said.
When the radio system is upgraded later this year, a second siren will be installed at fire Station 10, about two miles away at Trestle Glen Boulevard and Paradise Drive, and 840 AM will become known as SNAP, the Siren Notification Alerting the Peninsula, Ayers said.
"This is a test to see what our coverage area is," Ayers said.
The siren is sounded through several horns pointed in different directions, Ayers said. Fire district personnel will be driving around the Tiburon and Belvedere areas and communicating by radio to report where they can hear it, Ayers said.
The Tiburon-Belvedere Office of Emergency Services is participating in the test.
The March 11 earthquake in Japan generated a 3-foot tidal surge on the Tiburon waterfront, but it occurred during low tide and caused no damage, Ayers said.
Waterfront residents with landline phones are currently alerted to emergencies via a computer that makes reverse 911 calls. Notifications are also posted on the town's website, Ayers said.