Last week, the county discovered that five out of eight sirens do not work. Those sirens are supposed to provide tsunami warnings along roughly 30 miles of coastline from Pacifica to Pescadero.
County officials say repair work should be finished by early September. Until then, extra police and sheriff's deputies will be on-hand to alert the public in the event of a disaster.
Text alerts, emails and telephone warnings will also be used in case of emergency.