Topline:
A massive earthquake, one of the largest in the last century, has generated a tsunami advisory for much of the West Coast, as well as alerts for Alaska and many Pacific islands.
What to know about tsunamis: Risks differ depending on a number of factors. Generally speaking, Southern California is less likely to see a tsunami than Northern California.
Read on ... for more on what to watch for and why you should take advisories seriously.
On Tuesday afternoon, a massive earthquake hit off the coast of eastern Russia.
The quake, one of the largest in the last century, has generated a tsunami advisory for much of the West Coast, as well as alerts Alaska and many Pacific islands.
The size of this quake and the wide tsunami advisory had us going back to a question we explored the last time a quake of this magnitude hit offshore: What would it take for a tsunami to hit the California Coast?
To answer that question, we're revisiting an interview LAist did with Elizabeth Cochran in 2016. She's a seismologist with the U.S. Geological Survey. She left us with these takeaways:
"If we had a subduction zone event — that's where you would have the sea floor being pushed upwards and as a result the water would also be pushed upwards and then flow away from that spot — that's when you get a tsunami generated," Cochran explained. She added: "Going up farther north in California and into Oregon and Washington, there's a pretty high hazard for tsunamis if there's a large earthquake."
Cochran told us in 2016 — when a magnitude 6.5 earthquake hit 100 miles off the coast of Eureka — that the area was "fairly active for earthquakes."
That quake was felt justly slightly on land and did not result in a tsunami. But, she cautioned, distance from land didn't mean the coast was safe.
"We could have a tsunami affect the entire West Coast of the U.S. from a large magnitude earthquake that occurs as far away as Alaska or even in Japan," Cochran said. "So you can have these tsunamis that travel across the entire ocean basin and affect regions fairly far away. We have seen that in the past with some larger events."
Cochran noted that several factors go into when a tsunami hits ground.
"It depends how far away you are from where that earthquake occurs and where that tsunami is generated," she said. "Tsunamis travel approximately at the speed of a jumbo jet so it can actually take hours for a tsunami to transverse across the Pacific Ocean."
She said that the good news is there's a system in place to monitor ocean activity.
"For those types of events where you're looking at tsunamis generated far away, there are a number of ocean buoys that detect the tsunami and can be used to issue a warning," Cochran explained. "It's more difficult for local tsunamis because the time is, of course, quite a bit shorter. They can occur within minutes of the earthquake. That's why the recommendation is, if you're near the coast and you feel strong shaking, that you should move inland."
Cochran said we should always take any warnings seriously and to stay away from the beaches. If you ever feel a quake near the ocean, always move inland just to be safe.
For more information on the dangers faced in your area and evacuation procedures, visit the Governor's Office of Emergency Services website, MyHazards. Note: A version of this story also ran in late 2024 after 7.0 earthquake shook parts of Northern California and briefly prompted a wide tsunami warning.
We don't want to scare you, but a Big One is coming to Southern California. We don't know when, but we know it'll be at least 44 times stronger than Northridge and 11 times stronger than the Ridgecrest quakes in 2019. To help you get prepared, we've compiled a handy reading list: