Tsunamis

A  tsunami is a series of waves created by a sudden, significant displacement of the ocean floor.  They can be generated  by an underwater earthquake or landslide. In the event of a tsunami- always go to higher ground.

Tsunami waves may be generated by an event thousands of miles away (Distant Source) and take several hours to reach our coast. They may also be  generated locally (Local    Source) and arrive in as little as 10-15 minutes,   before there is time for an official warning from local emergency notification systems.  Experts have determined that a Local Source tsunami that produces significant damage is extremely unlikely to occur in San Francisco.

How might a tsunami affect San Francisco?
The City’s western tsunami inundation zone runs along the Pacific coast. If a tsunami should occur, people in the    inundation zone are at risk.

How will I know if a tsunami is approaching?

  • Outdoor Public Warning System sirens will sound.
  • AlertSF, NOAA Weather Radios and  Emergency Alert System broadcasts will also be used to notify the public of potential tsunamis. Tune in to your radio to KCBS 740 AM or other local station for information.
  • If you are on or near the beach and observe the water receding in an unusually rapid manner, immediately evacuate eastward to higher ground—even if no official warning has been issued.

What if I live on Treasure Island?

  • If you are on Treasure Island during a Tsunami go to higher ground in a Local Source as quickly as possible.
  • If it is a distant source Tsunamis,  carpool and pick up any neighbors or friends and evacuate the island. Transportation will be provided for those with special needs.