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San Mateo County authorities called off a test of its new tsunami sirens Wednesday due to engineering work being done on the system.
The entire system is projected to be in operation within the next few days.
There have been several major earthquakes around the Pacific Ocean in the past 24 hours, including 6.5-magnitude quakes off the coast of Alaska and Japan. However, none of these quakes triggered tsunami warnings.
The sirens are a reminder of the 2011 earthquake in Japan that sent a tsunami crashing onto the California coast. Images of cars trying to escape to higher ground in Half Moon Bay are still fresh in people's minds.
San Mateo County says its tsunami warning system was due for a replacement. The county has installed eight new sirens along the coast.
Tsunamis are a rare but real threat in California. After the 2011 Japan disaster, tsunami waves surged across Pacific at 500 mph and damaged the Northern California commercial fishing village of Crescent City.
U.S. Geological Survey scientists say a closer offshore quake would create more havoc, forcing coastal communities to evacuate and destroying boats and small craft.