US authorities put out tsunami warnings on Wednesday after an earthquake of magnitude 7.8 struck off Russia's Kuril Islands, but meteorological officials in Japan issued no alerts, although they said there might be slight tidal changes.

The U.S. National Oceanic and Atmospheric Administration said a tsunami watch was issued for the state of Hawaii, while another agency, the Pacific Tsunami Warning Center, said the quake had potential to generate a destructive tsunami.

Tsunami
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Tsunami warning

"Tsunami waves are forecast to be less than 0.3 meters above the tide level," the center said in its advisory about risks to the coasts of Hawaii, Japan, Russia and the Pacific islands of Midway, the Northern Marianas and Wake Island.

The height is equivalent to just under afoot.

The Japan Meteorological Association warned against slight tidal changes but said no warnings or even watch advisories had been issued.

The earthquake, 218 km (135 miles) south-southeast of the town of Severo, struck at a depth of 56.7 km (35 miles), the U.S. Geological Survey (USGS) said.

There were no immediate reports of damage or casualties.