One of the strongest earthquakes ever recorded struck off Russia’s sparsely populated Far East early Wednesday, sending tsunami waves into Japan, Hawaii and the US West Coast. Several people were injured, but none gravely, and no major damage has been reported so far.

Authorities warned the risk from the 8.8 magnitude quake could last for hours, and millions of people potentially in the path of the waves were initially told to move away from the shore or seek high ground.

Warnings were lifted or downgraded in Japan, Hawaii and the affected parts of Russia later Wednesday.

But Chile upgraded its warning to the highest level for most of its lengthy Pacific coast, and said it was evacuating hundreds of people.

In the immediate aftermath of the quake off Russia’s Kamchatka peninsula, residents fled inland as ports flooded, and several were injured while rushing to leave buildings.

Cars jammed streets and highways in Honolulu, with standstill traffic even in areas away from the sea.

In Japan, dozens of people flocked to evacuation centres, hilltop parks and rooftops in towns on the Pacific coast with fresh memories of the 2011 earthquake and tsunami that caused a nuclear disaster.

Tsunami advisories were also in place along much of the US West Coast and for the Canadian province of British Columbia.

Unusually strong currents and unpredictable surges were expected in places as far away as New Zealand.

The US National Weather Service warned the San Francisco Bay Area could see “some seriously dangerous currents along beaches and harbours.”

The earthquake appeared to be the strongest recorded since the 9.0 magnitude earthquake off northeastern Japan in March 2011 that caused a massive tsunami that set off meltdowns at a nuclear power plant.

No abnormalities in operations at Japan’s nuclear plants were reported on Wednesday.

The quake struck at 11.24am in Kamchatka with a magnitude of 8.8 and a depth of about 21 kilometres, according to the US Geological Survey. It was centred offshore, about 120 kilometres from Petropavlovsk-Kamchatsky, Kamchatka’s regional capital.

Multiple aftershocks as strong as 6.9 magnitude followed.

Russia’s Oceanology Institute said tsunami waves might have been as high as 10 to 15 metres in some sections of the Kamchatka coast, but the highest were less than 6 metres near the populated areas of the peninsula and the nearby Kurils islands.

Authorities in Hawaii downgraded the state to a tsunami advisory as Wednesday began, and evacuation orders on the Big Island and Oahu, the most populated island, were lifted.

“As you return home, still stay off the beach and stay out of the water,” said James Barros, administrator of the Hawaii Emergency Management Agency.

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.

In Northern California, tsunami activity continued to build on Wednesday morning with maximum confirmed heights along the coast of 1.1 metres in Crescent City.

In Petropavlovsk-Kamchatsky, Kamchatka’s regional capital, the quake damaged a local kindergarten, which was not in operation at the time because it was being renovated.

Oleg Melnikov, head of the regional health department, said several people hurt themselves while rushing to leave buildings and a hospital patient was injured while jumping out of a window. Melnikov said that all injured people were stable.

A video released by Russian media outlet showed a team of doctors at a cancer clinic on Kamchatka holding a patient and clutching medical equipment as the quake rocked an operating room, before continuing with surgery after the shaking stopped.

Authorities introduced a state of emergency on the sparsely populated Kurils, which are near Kamchatka, after the tsunami.

They earlier reported that several waves flooded the fishing port of Severo-Kurilsk, the main city on the islands, and cut power supplies to the area. The port’s mayor said no major damage was recorded.

In Japan, a tsunami of 60 centimetres was recorded in Hamanaka town in Hokkaido and Kuji port in Iwate, according to the Japan Meteorological Agency.

Several areas reported smaller waves, including 20 centimetres in Tokyo Bay five hours after the quake.

At least one person was injured.

In Toyokoro town in Hokkaido, about 20 people took refuge on top of a municipal building before moving to an inland town shelter where emergency food and water were available.

In Iwaki city in Fukushima, which was thew epicentre of the 2011 tsunami and quake, dozens of residents gathered at a hilltop park after a community siren sounded and breakwater gates were closed.

About 4,000 workers at the Fukushima Daiichi nuclear plant, severely damaged in the 2011 disaster, took shelter on higher ground at the complex while remotely monitoring operations, the operator said.

The International Atomic Energy Agency said initial reports showed that there has been no impact to the safety of nuclear power plants along Japan’s Pacific coast.

By late Wednesday, Japan had downgraded its tsunami alert, but left an advisory in place along the Pacific coast. (AP)