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Tsunami advisory issued for parts of the U.S. after undersea volcano erupts: What to know

An undersea volcano in the Pacific Ocean has triggered tsunami warnings on the West Coast and in Alaska. Here's what to watch for and how to stay safe.

A tsunami advisory has been put in place on parts of the West Coast after a volcanic eruption in Pacific Ocean.

The advisory affects the coastline of California, Oregon and Washington state, as well as parts of Hawaii, south Alaska and the Aleutian islands.

The Pacific Island nation of Tonga has been under a tsunami warning since the undersea Hunga Tonga Hunga Ha’apai volcano began erupting Saturday morning.

While there are "no tsunami observations are available to report" on the West Coast or in Alaska currently, the U.S. Tsunami Warning System will continue to update every 30 minutes. In Hawaii, "some impacts" are expected.

"Tsunami waves that can be a hazard to swimmers and boaters as well as to persons near the shore at beaches and in harbors and marinas are now affecting the state of Hawaii," said the National Tsunami Warning Center in an alert, noting that the "hazard could continue for several hours."

What are the signs of a tsunami?

While the signs of a tsunami can vary, there are a few things to watch out for. The National Tsunami Warning Center advises paying attention to your surroundings and keeping an eye out for sudden changes, including the following:

  • A rapidly receding or receded shoreline
  • Unusual waves and sounds
  • Strong currents

A tsunami may also appear as water moving rapidly out to sea, as a gentle rising tide with no breaking wave, as a series of breaking waves or as a frothy wall of water, according to the center. Feelings of an earthquake can also precede a tsunami.

What should I do during a tsunami advisory?

According to the National Tsunami Warning Center, there are some simple things anyone under a tsunami advisory can do to reduce the risk to human life and property.

The first thing the center recommends is moving away from water, including harbors, marinas, breakwaters, bays and inlets. Be sure to stay off the beach.

It's also important to stay aware of your surroundings: Keep an eye out for instructions from local emergency officials, who may have more detailed or specific information, and if you feel a strong earthquake or extended ground rolling, move inland and uphill as quickly as possible.

Anyone currently at sea during a tsunami advisory should avoid entering shallow water.

While the impact of a tsunami can vary, strong waves and currents can drown or injure people in the water or close to shore. Currents in unexpected places, like at harbors or in bays, may be especially dangerous. Waves can last between five and 45 minutes, according to the National Tsunami Warning Center, and coasts in all directions may be threatened because of the movement of the water.