Much of the West Coast of the U.S. is under tsunami alerts, after one of the largest earthquakes ever recorded struck eastern Russia and sent powerful waves into Japan, Hawaii, California and counting.

A magnitude 8.8 earthquake hit near Russia's sparsely populated Kamchatka Peninsula on Wednesday morning local time — tying with two other quakes to become the sixth-strongest ever recorded on Earth, according to U.S. Geological Survey data.

Wednesday's temblor flooded ports, damaged buildings and injured several people, according to Russian state news agency Tass, which also cites the Kremlin as saying there were no casualties.

The earthquake triggered tsunami advisories and evacuation orders across much of the Pacific, where fears of powerful waves had many people scrambling overnight.

As of Wednesday morning, both Hawaii and Japan have experienced tsunami waves but no substantial damage or injuries. Even after local officials downgraded their alerts, they are warning people to remain cautious along the coasts.

"We went into this tsunami warning, we got out of the area, we were safe — let's return back and be safe," James Barros, administrator for the Hawaii Emergency Management Agency, said at an overnight press conference, urging people to watch for floodwaters and check their structures as they return home.

Coastal areas of Alaska, California, Oregon and Washington state are waking up to tsunami alerts and growing activity, according to the National Weather Service (NWS).

Officials are urging people to avoid beaches, waterways and shores for the foreseeable future, warning that tsunamis are a series of waves over the course of multiple hours. The first wave, they stress, may not be the largest.