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San Diego Emergency Officials, Geologist Sound Alarm On Tsunami Risk

Photo by Susan Murphy

Cindy Pridmore, geologist with the California Geological Survey talks about San Diego's tsunami risk during a news conference at La Jolla Shores, March 23, 2017.

If a large earthquake struck offshore, thousands of people along San Diego’s 70 miles of coastline could be in danger.

If a large earthquake struck offshore, thousands of people along San Diego’s 70 miles of coastline could be in danger.

“So the big message is, if you’re on the coastline and you feel an earthquake, we want you to get away from the water,” said Cindy Pridmore, geologist with the California Geological Survey.

Pridmore teamed up on Thursday with state and local emergency officials at La Jolla Shores to remind the public of the region’s tsunami risk. The event was part of Tsunami Preparedness Week.

“These are infrequent events that can have catastrophic consequences,” Pridmore said.

Tsunamis are often triggered by earthquakes on thrust faults that push up on the ocean floor, generating large waves. Most of San Diego’s offshore faults, such as the notorious Rose Canyon, are strike-slip faults that pose little tsunami risk.

San Diego Emergency Officials, Geologist Sound Alarm On Tsunami Risk

But there are several thrust faults offshore from California capable of producing large waves that could hit the San Diego shoreline within minutes, Pridmore said.

“The other one consideration we have for San Diego is, offshore we have a canyon, a submarine canyon,” Pridmore explained. “If there’s strong shaking, a chunk of that could cause a tsunami.”

Low-lying regions would experience the biggest impacts, such as Mission Bay and Coronado. County officials have mapped out which neighborhoods along the coast are at high risk for flooding. They also recently created a “tsunami response playbook.”

“Instead of a one-size-fits-all response for all communities, each coastal city and U.S. Naval installation now has a playbook that outlines response actions specific to their topography, their inundation zones and their population,” said Michael Davis, with the San Diego County Office of Emergency Services.

Davis said the playbook reduces the threat of over-evacuation that could cause additional hazards in the event of a disaster.

San Diego has experienced nearly a dozen small tsunamis over the past 200 years.

Signs of a tsunami include a receding shoreline and a large ocean roaring sound. People who are near the coastline during an earthquake are advised to evacuate to at least 100 feet above sea level or two miles inland.

Residents are also urged to register their mobile phones with Alert San Diego at readysandiego.org to receive emergency notifications.

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