The West Coast is under a tsunami advisory. Here’s what that means.

Catastrophic waves are unlikely, but residents should be cautious.
choppy waves on a beach with a sign warning people not to swim
The underwater eruption could put US coastal communities in danger. Jonah Brown via Unsplash

A massive volcanic eruption sent tsunami waves into the Pacific nation of Tonga on Saturday. This led to tsunami advisories for Hawaii and the entire Western coast of the United States.

According to the Pacific Tsunami Warning Center, the Hawaiian islands have so far experienced only minor flooding from the event. While there are no catastrophic waves anticipated in the continental US, coastal residents should still take precautions. Powerful and dangerous currents are possible, according to the NWS National Tsunami Warning Center, as well as perilous waves. At the very least, people close to the coast are advised to “move out of the water, off the beach, and away from harbors, marinas, breakwaters, bays and inlets.” Do not go to the shore in an attempt to observe the tsunami waves. Read more about when tsunami conditions are forecasted to begin in your area here.

[Related: How to survive a tsunami.]

Tsunamis result from earthquakes, deep sea volcanic eruptions, and submarine landslides. Wave heights can build as they move from deep water into shallower coastal areas, making it possible for massive and dangerous waves to hit coasts far from the initial disturbance.

The Hunga-Tonga-Hunga-Ha’apai volcano, which is located around 19 miles southeast of Tonga’s Fonuafo’ou island, erupted once on Friday and once on Saturday. The BBC reports that the initial eruption, which lasted for eight minutes, “could be heard as ‘loud thunder sounds'” as far as 500 miles away in Fiji. Tonga’s largest island, Tongatapu, was hit with violent waves and flooding, as well as clouds of ash and volcanic debris.

Residents of areas under advisory should keep an eye on emergency alerts. In the event of an upgrade to a tsunami warning, they should immediately move inland or seek high ground—on foot, if possible, to avoid becoming stuck in traffic with other evacuees.