San Francisco Tsunami: What Will Happen if Tidal Sea Wave Hits Bay Area? Regions Most At-Risk Revealed

San Francisco is not prone to tsunamis, but the city is already preparing. In 2022, the San Francisco Department of Emergency Management asked the residents to understand tsunami risk and learn how to respond.

San Francisco Tsunami

According to Mary Ellen Carrol, the Department of Emergency Management Executive Director, whether one lives, works, or travels along the coast, one must be equipped to respond to a tsunami emergency. Carrol said that San Fransisco's tsunami risk is low, but it is important to learn more about it, including when and where it could occur, to limit its impact.

On April 18, 1908, a tsunami was recorded at the Presidio tide gauge station shortly after the Great San Francisco earthquake. Despite a strong 7.8 magnitude tremor, the 1906 earthquake only produced a tsunami wave around 10 cm tall. On the other hand, a tsunami resulting from a subduction zone earthquake of comparable magnitude in other Pacific basin border regions would have, on average, produced a significantly greater tsunami.

SF's Tsunami Response Plan is kept up to date by the Department of Emergency Management (DEM), the primary agency for responding to tsunamis. When a tsunami struck adjacent islands in January of this year due to an underwater volcano eruption near Tonga, the city's Tsunami Response Plan was put into action. That eruption caused a tsunami advisory to be issued for San Francisco.

In accordance with the recommendation, the city's AlertSF emergency notification system has to be turned on, along with synchronized emergency public information.

The Department of Emergency Management urges San Franciscans to be ready and aware of their options in the case of a tsunami. It urged the residents to connect to city emergency alerts and follow DEM on Facebook, Nextdoor, and Twitter.

Residents can also visit www.sf72.org/hazard/tsunamis and enter their address into a map to learn if their area of residence or work is in a tsunami inundation zone and know where the designated tsunami evacuation centers are.

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Tsunami Hazard Maps

State geologists are working hard to keep the Bay Area safe from tsunamis or at least limit its effect in case it hits them. They designed hazard maps for San Francisco and East Bay, where a major tsunami could strike.

Rick Wilson from the California Geological Survey said they didn't want to scare people by giving them maps of an extreme event they wouldn't see in their lifetime. However, the team believes it's best to prepare for the worst.

California Geological Survey updated its tsunami hazard maps from 2009 using new technology. Pr, Adrienne Bechelli, Deputy Director of San Francisco's Department of Emergency Management, said that a 9.3 magnitude earthquake off Alaska would be the worst case for San Francisco.

Based on the East Bay, it could bring tsunami waves into parts of West Oakland and Lake Merritt. In San Francisco's waterfront, the surge could reach the Financial District as far as Fremont Street. The tsunami waves could also reach parts of North Beach from Fisherman's Wharf.

Wilson added that tsunami heights may not be large in the Bay Area. However, there's still a potential that it could knock people down and injure them.