Anxiety, fear and confusion spread across the West Coast early Thursday as a rare tsunami warning was issued for parts of northern California and southern Oregon following a magnitude 7 earthquake that struck about 55 miles off the coast of Eureka.

Evacuations were ordered. Sirens went off. Bay Area commuter rail service through the underwater Transbay Tube ceased.

But after about an hour the warning was lifted. Although the circumstances were favorable, there was no major tsunami this time.

“It could have moved a lot of water,” said Dave Snider, the tsunami warning coordinator at the National Tsunami Warning Center in Alaska. “We’re glad that wasn’t the case.”

The conditions could have led to a dangerous tsunami, but there is no way to accurately predict such an event in advance, Snider said. So his team errs on the side of caution, especially if the earthquake hits closer to the coast – like this one – and could flood populated areas more quickly.

“We are reacting completely reactionary to the earthquake event,” said Snider. “Time must be respected to ensure people’s safety.”

Tsunami warnings remain rare for the West Coast, and actual large tsunamis are even more unusual, Snider said. But they do happen, so it’s important that residents are prepared and know how to respond.

He said Thursday’s incident was a good reason to “update what it means to live in a tsunami country.”

A Brief History of the California Tsunamis

Here’s what we know from Times reports and state records about past tsunamis in California:

The last time the U.S. West Coast received a tsunami warning was in January 2022, Snider said, after the eruption of an underwater volcano in a remote corner of the South Pacific triggered a massive tsunami.

In California, the impact was relatively minor, but at Santa Cruz Harbor, waves swamped streets and a parking lot where cars floated around like toy boats. Water flowed into bathrooms and electrical transformers on land. It caused an estimated $6 million in damage in Santa Cruz alone, officials later said.

In 2011, a tsunami from the devastating Japan earthquake also devastated some coastal areas of California, causing more than $100 million in damage to marinas and harbors, according to state officials’ estimates. In Crescent City, residents reported that about three dozen boats were “crushed” in the harbor and that the rising water significantly damaged or destroyed many docks.

One person died after reportedly being swept into the sea while photographing the tsunami.

The Del Norte County city has experienced two other tsunamis in recent history. In 2006, Crescent City residents were surprised by a significant rise in seawater hours after a tsunami warning expired, causing significant damage to the harbor.

Most notably, the 1964 Alaska earthquake triggered a catastrophic tsunami that devastated Crescent City, washing away 29 city blocks and killing at least 11 people. A series of overnight waves crashed across the coastal town, destroying or damaging 91 homes and 172 businesses.

California authorities also have records of tsunamis that struck Northern California in 1960 and 1946, each killing at least one person. The 1946 tsunami, triggered by a magnitude 8.6 earthquake near Alaska, flooded parts of Half Moon Bay.

Among the earliest records of a tsunami in California was an 1812 event when a large earthquake in the Santa Barbara area was followed by “a tsunami that wiped out many coastal villages and destroyed ships in harbor,” according to the U.S. Geological Survey.

And there was the catastrophic mega-tsunami of 1700, which was caused by a magnitude 9 earthquake across the Cascadia fault system, which runs 700 miles off the coast from Northern California to Vancouver Island.

This earthquake was so strong that entire sections of the Pacific coast fell by up to 1.5 meters. In the Pacific Northwest, Native Americans told stories of “how the prairie became the ocean” and canoes were thrown into trees.

If a similar earthquake were to occur today, scientists say a huge tsunami would wash away coastal cities, destroy US 101 and cause $70 billion in damage across a large swath of the Pacific coast. More than 100 bridges would be lost, power lines collapsed and coastal towns isolated. According to a scenario published more than a decade ago, residents would have just 15 minutes’ notice to flee to higher ground and up to 10,000 would perish.

Can you prepare for a tsunami?

As Snider noted, these rare systems are difficult to predict, but there are ways to prepare and know what factors can trigger such dangerous events.

Natural warning signs include the feeling of a strong or prolonged earthquake. If you’re on the beach and see a sudden rise or fall of the ocean or hear a loud roar, it’s time to head inland.

“If you are on the beach or in a harbor and feel an earthquake, immediately move inland or get to high ground. If strong shaking lasts 20 seconds or longer, everyone in the tsunami evacuation area should evacuate as soon as it is safe to do so,” says the California Geological Survey.

Use caution if you live in or frequently visit a tsunami evacuation zone. The California Geological Survey has online maps of tsunami hazard areas throughout the state. In Southern California, this includes areas in or around Ventura, Oxnard, Malibu, Venice, Marina del Rey, Hermosa Beach, Redondo Beach, the Ports of Los Angeles and Long Beach, Long Beach, Seal Beach, Sunset Beach, Huntington Beach and Newport Beach.

In the San Francisco Bay Area, areas at risk include the westernmost areas in Richmond and Sunset counties in San Francisco, as well as the Marina District and areas along the Embarcadero, affecting a significant portion of the Financial District and South of Market areas .

Keep an eye out for tsunami hazard maps in your area. If maps or signs are not available, state officials recommend going to an area 100 feet above sea level or two miles inland. “If you can’t get that far, go as high as you can. Every foot inland or up can make a difference,” state officials say.

The National Weather Service operates two tsunami warning centers with the goal of monitoring tsunamis and earthquakes they could cause and sending tsunami warnings. To receive official notification of a tsunami warning, sign up for text message alerts from your local government, get a battery-powered NOAA weather radio, or listen for television, radio or automated telephone announcements.

Sign up for alerts here:

How should you react after a tsunami warning?

Leave the area on foot and move to higher ground. Do not get into your car or attempt to drive away from the danger area – evacuating by car could result in a traffic jam.

If you feel the earthquake: Fall to the ground, take cover, and hold on until the shaking stops.

If you have been evacuated from a coastal area, stay away until authorities allow you to return. Don’t go to the coast to watch a tsunami. Tsunamis move faster than a human can walk.

Don’t be discouraged after the first tsunami wave. The first is usually not the highest. Large tsunami waves can reach heights of more than 50 feet in some coastal areas. Tsunami waves can last for hours.

Don’t try to surf or watch a tsunami. You can’t surf a tsunami because a tsunami wave has no face. Regular waves flow in circles without flooding higher areas. Tsunami waves are unpredictable and flood the country like a wall of water.

Times staff writer Rong-Gong Lin II contributed to this report.