Magnitude 8.8 earthquake off Russia sparks Pacific tsunami warnings

TOKYO: Tsunamis hit parts of Russia's Far East and Japan on Wednesday after a huge magnitude 8.8 earthquake, with warnings in place around the Pacific of waves of over three metres (10 feet) in places.

Russia's emergencies ministry said a tsunami hit and flooded the port town of Severo-Kurilsk, where the population of around 2,000 people was evacuated.

A video posted on Russian social media appeared to show buildings in the town submerged in seawater.

Several people were injured in Russia by the quake, state media reported, but none of them seriously.

Live footage on Japanese television showed people evacuating by car or on foot to higher ground, including the northern island of Hokkaido, where the first wave, measuring 30 centimetres (one foot) was observed.

Wednesday's quake was the strongest since 1952 in Russia's Kamchatka region, the Geophysical Service of the Russian Academy of Sciences reported.

The epicenter of the earthquake is roughly the same as the massive 9.0 temblor that year which resulted in a destructive, Pacific-wide tsunami, according to the USGS.

At least six aftershocks have further rattled the region, including one of 6.9 magnitude and another listed at 6.3.

Japanese broadcaster NHK switched to special coverage, with presenters telling people on the coast to "please evacuate immediately".

Its screen showed the messages "Tsunami! Evacuate!"

Workers at the stricken Fukushima nuclear plant in northeast Japan - destroyed by a huge quake and tsunami in 2011 - were evacuated, its operator said.

Japan's weather agency initially warned that the waves would be up to one metre high, but this was later upgraded to a much more potentially dangerous three metres.

This covered all the way down the northern and eastern coasts of Japan as far as Wakayama, south of Osaka, as well as outlying smaller islands.

Beyond that, as well as in the Tokyo Bay and Osaka Bay, the waves were forecast to be one metre high and to hit between 10:00 am and 11:30 am (0100-0230 GMT).

The US Geological Survey (USGS) initially said the tremor measured 8.0 but then upgraded the reading to 8.8.

The US Tsunami Warning Centers said the waves exceeding three metres above the tide level were possible along some coasts of Ecuador, northwestern Hawaiian islands and Russia.

Between one- and three-metre waves were possible along some coasts of Chile, Costa Rica, French Polynesia, Guam, Hawaii, Japan and other islands and island groups in the Pacific, it said.

Waves of up to one metre were possible elsewhere, including Australia, Colombia, Mexico, New Zealand, Tonga and Taiwan.

It described the potential conditions as "hazardous."

The United States further sounded the alarm with a series of alerts of varying levels along North America's West Coast, from Alaska down to the entire coast of California.

Tsunami alerts were pushed to mobile phones in California, according to local AFP reporters.

The Japan Meteorological Agency warned on X that "tsunamis will strike repeatedly. Do not enter the sea or approach the coast until the warning is lifted."

"Residents in regions where warnings have been issued should immediately evacuate to safe locations such as elevated areas or evacuation buildings," top government spokesman Yoshimasa Hayashi said in a short-notice brief news conference.

Some train lines in Japan were suspended due to the alert, including lines serving the coast around Chiba, Yokohama, Fujisawa and down the Izu coast.

The Philippines urged residents living along the eastern seaboard to move further inland, predicting tsunami waves of as high as one metre to arrive between 1:20 pm and 2:40 pm (0520-0640 GMT).

"People are also advised to stay away from the beach and not to go to the coast ... until the cancellation of the advisory," the seismology centre said in a warning.

The warning also advised fishermen already out to sea to stay offshore in deep waters until the threat passed.

Here are key facts about tsunamis and the damage they can cause:

A tsunami is a shock of water that spreads through the sea, usually triggered by a strong earthquake beneath the ocean floor.

The sudden, violent movement of the Earth's crust can thrust up or drive down a section of the seabed - with the rift displacing vast quantities of water that move as waves.

Tsunamis radiate in all directions from their source and can cover enormous distances, sometimes at the speed of a jet plane.

They are a rare phenomenon but can create dangerously powerful currents and cause deadly flooding in coastal areas.

Large quakes are the main driver of tsunamis, but the phenomenon can also be sparked by other cataclysmic geographic events, such as volcanic eruptions and landslides.

In 1883, a volcano shattered the Pacific island of Krakatoa, causing a blast that could be heard 4,500 kilometres (2,800 miles) away, followed by a tsunami that killed around 30,000 people.

Large storms or a meteorite falling into the ocean can also be powerful enough to cause a tsunami, according to the US National Oceanic and Atmospheric Administration.

The word "tsunami" comes from the Japanese words for "harbour" and "wave".

Tsunamis are sometimes referred to as "tidal waves" but experts say this is inaccurate because they are not related to tides.

At their point of generation, tsunamis have a relatively small wave height, with peaks far apart.

As the waves approach the shore they are compressed by the shelving of the sea floor, reducing the distance between the peaks and vastly increasing the height.

When they hit the coast, tsunami waves can strike repeatedly over several hours, or even days.

To those on the shore, the first sign of something amiss can be the retreat of the sea, which is followed by the arrival of large waves.

"The sea was driven back, and its waters flowed away to such an extent that the deep seabed was laid bare and many kinds of sea creatures could be seen," wrote Roman author Ammianus Marcellinus of a tsunami that struck Alexandria in 365 AD.

"Huge masses of water flowed back when least expected, and now overwhelmed and killed many thousands of people... some great ships were hurled by the fury of the waves onto the rooftops."

Several factors determine the height and destructiveness of a tsunami.

They include the size of the quake, the volume of displaced water, the topography of the sea floor and whether there are natural obstacles that dampen the shock.

The Pacific Ocean is particularly prone to earthquakes and therefore to tsunamis, but over the millennia tsunamis have occurred in many parts of the world.

The tsunami of December 2004 in the Indian Ocean was caused by a 9.1 magnitude earthquake off the Indonesian island of Sumatra.

It released energy equivalent to 23,000 of the atomic bombs dropped on Hiroshima, according to the US Geological Survey (USGS). Around 220,000 people in 11 nations were killed, many of them thousands of kilometres from the epicentre.