Following two unscheduled activations of San Francisco's outdoor emergency siren system last weekend, the regularly scheduled emergency system test that occurs at noon each Tuesday happened as planned, according to the Department of Emergency Management.
The 112 sirens that make up the emergency system, located on poles and atop buildings throughout all neighborhoods including Treasure Island and Yerba Buena Island, are designed to alert city residents and visitors about possible danger, department spokesman Francis Zamora said.
The system allows for specific emergency announcements to be broadcast over any and all of the speakers to alert residents about emergencies such as earthquakes or tsunamis.
Alarms sounded unexpectedly about 11 p.m. Saturday in Bernal Heights, Noe Valley, Hunters Point, the Bayview and Civic Center, among other areas, despite no actual emergency, Zamora said. Alarms then went off again about 5 a.m. Sunday.
The cause of the siren activation is under review and the system's hardware and software are being examined, Zamora said.
The vendor, Acoustic Technology, has also been asked to review the notification system, Zamora said.
During the weekly Tuesday test, the sirens emit a 15-second alert tone, similar to the siren sounded by emergency vehicles, Zamora said. In the event of an emergency, the 15-second alert will sound repeatedly for five minutes.
Several people called 911 to report the sirens over the weekend and dispatch centers were notified about the alarms going off.
In the event of a real emergency, the city will also utilize its text and email alert system that people can register for at www.alertsf.org. The City will also post information through its accounts on Facebook at and www.facebook.com/sf72org, via the Twitter handles @SF_emergency and @SF72org, and on Nextdoor at www.nextdoor.com.