The idea of underwater earthquake/landslides causing tsunamis is not new. They may well have been the cause of disastrous tsunamis in Santa Barbara (1812) and Point Arguello (1927). But only recently have scientists begun to discover areas off the San Diego coast where potential tsunami generating landslides have occurred in the past and could occur in the future. For example, according to U.S. Geological Survey (USGS), new seafloor data has revealed huge landslide scars along the steep slopes of the continental shelf off Huntington beach, Palos Verdes, and five miles off the coast of Del Mar.
In the case of a local underwater landslide, residents would have only several minutes to evacuate and little time for emergency services to assist.
Distant incidents include large earthquakes in areas like Alaska, Chile, or Japan, and their tsunami waves take hours to arrive in San Diego. Each earthquake of magnitude 7.1 or larger is monitored by NOAA’s tsunami warning centers, which issue warnings within 15 minutes of the quake. Depending on the alert, San Diego emergency services will activate emergency local alerts for affected areas.
Worst Case Scenario? San Diego County Emergency Services Have It Covered
1:00 a.m. People are sleeping and their electronics are off. A 9.1 magnitude earthquake occurs off Alaska and large tsunami waves begin rolling towards San Diego.
“We have a thoroughly vetted tsunami evacuation plan,” says Del Mar Community Services Director & Chief Lifeguard Pat Vergne. “It doesn’t matter what time it is or where we are, because if it is an ocean issue, our lifeguards will get the alert, come in to assess the situation, and take appropriate action.”
As in all San Diego County beach areas, emergency services - firefighters, sheriff, lifeguards, City and County offices, and military - work together to assure residents are safe. In close contact, they watch the NOAA alerts and use their extended networks to assess tsunami size and strength in real time.
“After the 2011 Japan quake, we were in contact with our counterparts on the beach in Hawaii when the waves hit," said Verne. "They were small enough that we knew with certainty we did not need to order an evacuation. If the waves had been larger, we would have worked in tandem with our firefighters, driving through the streets, announcing evacuation procedures over our loudspeakers, and helping those who needed it.”
What To Do in Case of a Tsunami:
According to Holly Crawford, San Diego County’s Office of Emergency Services Director, "If the earth shakes for 20 seconds, that’s a really significant earthquake. You need to leave the coast, go to a place that’s at least 100 feet above sea level or two miles inland if you can’t evacuate vertically."
During a tsunami warning, follow these suggestions:
- Do not go to watch the waves from the beach, or piers. Multiple people have been swept into the sea and drowned.
- Know your evacuation routes. Signs have been posted all over San Diego County to help direct traffic, however it’s best to have a plan ahead of time. Click here for a map of your area.
- Listen to the emergency alerts issued on television, radio, reverse 911 calls, social media, etc. They will provide instructions and updates for local communities. (Register your mobile phones at readysandiego.org to receive emergency notifications. Landlines are automatically included in the reverse 911 outreach.)
- Obey firefighters, lifeguards & police. Every beachfront community in San Diego has trained for tsunami evacuation.
- Take your "go bag"
- Have a designated safe location.
- Have a contact out of the tsunami zone with whom family members can check in.
- Do not return home until emergency responders give the all clear. Tsunami waves often roll in over several hours.
- Do not try to “ride it out.”
- Help any neighbors who are unable to evacuate due to physical or health restrictions.
- Call 211 for information. Only call 911 if you need assistance. Keep lines clear for those who need immediate help.
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