Moscow: One of the strongest earthquakes ever recorded struck Russia's Far East on Wednesday, sending tsunami waves into Japan and Hawaii and across the Pacific. No substantial damage has been reported so far, but authorities warned people away from shorelines and said the risk could last more than a day.

Ports on the Kamchatka Peninsula in Russia near the 8.8 magnitude quake's epicenter flooded as residents fled inland, and frothy, white waves washed up to the shore in northern Japan. Cars jammed streets and highways in Hawaii's capital, with standstill traffic even in areas away from the shoreline.

People went to evacuation centers in affected areas of Japan, with memories fresh of the 2011 earthquake and tsunami that caused reactor meltdowns at a nuclear power plant. No abnormalities in operations at Japan's nuclear plants were reported Wednesday.

Russian authorities said several people were injured, without giving a figure. In Japan, at least one person was injured. The quake at 8:25 am Japan time had a preliminary magnitude of 8.0, Japanese and US seismologists said. The US Geological Survey later updated its strength to 8.8 magnitude and a depth of 20.7 kilometers (13 miles).

The quake was centered about 119 kilometers (74 miles) east-southeast from the Russian city of Petropavlovsk-Kamchatsky, which has a population of 180,000, on the Kamchatka Peninsula. Multiple aftershocks as strong as 6.9 magnitude followed.

A tsunami height of 3-4 meters (10 to 13 feet) was recorded in Kamchatka, 60 centimeters (2 feet) on Japan's northern island of Hokkaido, and up to 1.4 feet (under 30 centimeters) above tide levels were observed in Alaska's Aleutian Islands.

The impact of the tsunami could last for hours or perhaps more than a day, said Dave Snider, tsunami warning coordinator with the National Tsunami Warning Center in Alaska

"A tsunami is not just one wave," he said. "It's a series of powerful waves over a long period of time. Tsunamis cross the ocean at hundreds of miles an hour -- as fast as a jet airplane -- in deep water. But when they get close to the shore, they slow down and start to pile up. And that's where that inundation problem becomes a little bit more possible there."

"In this case, because of the Earth basically sending out these huge ripples of water across the ocean, they're going to be moving back and forth for quite a while," which is why some communities may feel effects longer, he said.

Hawaii Gov Josh Green said data from Midway Atoll, which is between Japan and Hawaii, measured waves from peak to trough of 6 feet (1.8 meters). He said waves hitting Hawaii could be bigger or smaller and it was too early to tell how large they would be. A tsunami of that size would be akin to a 3-foot (90-centimeter) wave riding on top of surf, he said. "This is a longitudinal wave with great force driving through the shoreline and into land," he said at a news conference.

Green said Black Hawk helicopters have been activated and high-water vehicles were ready to go in case authorities need to rescue people. "But please do not put yourself in harm's way," he said.

The Oregon Department of Emergency Management said on Facebook that small tsunami waves were expected along the coast starting around 11:40 pm local time, with wave heights between 1 to 2 feet (30 to 60 centimeters). It urged people to stay away from beaches, harbors and marinas and to remain in a safe location away from the coast until the advisory is lifted.

"This is not a major tsunami, but dangerous currents and strong waves may pose a risk to those near the water," the department said.

Much of the West Coast, spanning California, Washington state, and the Canadian province of British Columbia, was also under a tsunami advisory.

A tsunami of less than 30 centimeters (under 1 foot) was forecast to hit parts of Vancouver Island, British Columbia. The province's emergency preparedness agency said waves were expected to reach remote Langara Island around 10:05 p.m. Tuesday and Tofino around 11:30 pm. The agency said "multiple waves over time" were expected.