Millions of people were told to move away from the shore or seek high ground because they were potentially in the path of the tsunami waves, which struck seaside areas of Japan, Hawaii and the U.S. West Coast but did not appear to cause any major damage.

The dire warnings following the massive quake early Wednesday off Russia’s Kamchatka peninsula evoked memories of catastrophic damage caused by tsunamis over the last quarter-century.

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

Cars jammed streets and highways in Honolulu, with traffic at a standstill even far from the sea.

“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.�

U.S. Secretary of Homeland Security Kristi Noem said the worst was over. Later Wednesday, tsunami advisories for Hawaii, Alaska, Oregon and Washington state were canceled but remained for parts of northern California, where authorities warned to stay away from beaches and advised that dangerous currents should be expected through Thursday morning.

Experts say it's challenging to know when to drop advisories, which signal the potential for strong currents, dangerous waves and flooding.

“It’s kind of hard to predict because this is such an impactful event and has created so many of these waves passing by,� said Dave Snider, tsunami warning coordinator for the National Tsunami Warning Center in Alaska.

Among the world’s strongest recorded quakes

The earthquake appeared to be the strongest recorded since the 9.0 magnitude earthquake off Japan in 2011 caused a massive tsunami and meltdowns at a nuclear power plant. The International Atomic Energy Agency said initial reports showed Japan’s nuclear plants were not affected this time.

Wednesday's quake occurred along the “Ring of Fire,� a series of seismic faults around the Pacific Ocean. It was centered offshore, about 120 kilometers (75 miles) from Petropavlovsk-Kamchatsky, Kamchatka’s regional capital. Multiple aftershocks as strong as 6.9 magnitude followed.

Russia’s Oceanology Institute said tsunami waves of less than 6 meters (20 feet) were recorded near populated areas of the peninsula.

Lava began flowing Wednesday from the Northern Hemisphere's largest volcano in a remote area of Kamchatka, the Russian Academy of Sciences’ geophysical service said.

Evacuations ordered in South America

Chile, a place highly vulnerable to earthquakes and tsunamis, raised its warning to the highest level early Wednesday for most of its lengthy Pacific coast and began evacuating hundreds of people.

“Remember that the first wave is usually not the strongest,� Chilean President Gabriel Boric warned on social media.

Colombian officials ordered the complete closure and evacuation of beaches and low-tide areas while maritime traffic was being restricted. Ecuador canceled classes at schools in the Galapagos Islands as well as communities along the coast.

Coastlines of New Zealand — about 6,000 miles (9,600 kilometers) from the quake’s epicenter — were experiencing strong currents and wave surges. There were no evacuations, but people throughout the South Pacific island nation were warned to stay out of the water and away from beaches, shorelines and harbors.

Hawaii downgrades to tsunami advisory

Authorities in Hawaii downgraded the state to a tsunami advisory early Wednesday, 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.

In northern California, tsunami activity continued Wednesday morning with waves of 3.6 feet (1.1 meters) in Crescent City, which has a history of tsunami disasters.

Even waves of just several feet high might pose a significant risk.

“It might only be 3 feet, but it’s a wall of water that’s 3 feet and spans hundreds of miles. Three feet of water can easily inundate inland and flood a couple blocks inland from the beach," said Diego Melgar, director of Cascadia Region Earthquake Science Center at the University of Oregon.

Russian regions report limited damage

In Petropavlovsk-Kamchatsky, the quake damaged a local kindergarten that was unoccupied.

A video released by a 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.

Authorities on the sparsely populated Kuril Islands reported 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.

Dozens in Japan find refuge on hilltops and on rooftops

A tsunami of 2 feet (60 centimeters) was recorded in Hamanaka town in Hokkaido and Kuji port in Iwate, according to the Japan Meteorological Agency. Several areas reported smaller waves, and at least one person was injured.

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

Workers at the Fukushima Daiichi nuclear plant, severely damaged in 2011, took shelter on higher ground while remotely monitoring operations, the operator said.

Hours later, Japan downgraded its tsunami alert but left an advisory in place along the Pacific coast.

Associated Press journalists from around the world contributed to this report.