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.

The worst appeared to have passed for many areas, including the US, Japan and the affected parts of Russia. But Chile raised its tsunami warning to the highest level for most of its lengthy Pacific coast and said it was evacuating hundreds of people.

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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.

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.

“We’ve got water, we got some snacks ... we’re going to stay elevated,” said Jimmy Markowski, whose family from Hot Springs, Arkansas, fled their Waikiki beach resort before evacuation orders were lifted. “This is our first tsunami warning ever. So this is all new to us.”

While tsunami advisories remain in place along much of the US West Coast, secretary of homeland security Kristi Noem said the worst was over.

“We were fully deployed and ready to respond if necessary, but grateful that we didn’t have to deal with the situation that this could have been,” she told reporters in Chile, where she is meeting officials.

Unusually strong currents and unpredictable surges were expected in places as far away as New Zealand, and the National Weather Service warned the San Francisco Bay Area could see “some seriously dangerous currents along beaches and harbours.”

Among the world’s strongest recorded quakes

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. The International Atomic Energy Agency said initial reports showed Japan’s nuclear plants were not affected Wednesday.

Only a few stronger earthquakes have ever been measured around the world. Wednesday’s occurred along the Pacific “Ring of Fire,” a series of seismic faults around the Pacific Ocean where most of the world’s earthquakes take place.

The quake struck at 2.24am Wednesday (9.24am AEST) in Kamchatka with a magnitude of 8.8 and a depth of about 21km, according to the US Geological Survey. It was centred offshore, about 120km 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 6m near the populated areas of the peninsula and the nearby Kuril islands.

Meanwhile, lava began to flow Wednesday from a volcano on Kamchatka, the largest active one in the Northern Hemisphere. Observers also heard explosions, the Kamchatka branch of the Russian Academy of Sciences’ geophysical service said.

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

Authorities in the Philippines, Mexico and New Zealand warned residents to watch for waves and strong currents. People were also urged to stay away from coastlines until any wave surges passed in Fiji, Samoa, Tonga, Federated States of Micronesia and Solomon Islands.