Earlier 5.0-magnitude and 6.7-magnitude earthquakes did not initially trigger a tsunami alert, but were followed by a 7.4-magnitude quake at 0849 GMT, prompting the USGS to warn that "hazardous tsunami waves are forecast for some coasts".

The USGS said it expected waves of between 30 centimetres and one metre (up to 3.3 feet) on Russian coasts, and less than 30 centimetres (one foot) in Japan and the US state of Hawaii.

The epicentre of the quakes was in the Pacific Ocean, around 150 kilometres (93 miles) east of the city of Petropavlovsk-Kamchatsky, it said.

The initial earthquakes were followed by several aftershocks, including another 6.7-magnitude quake, said USGS.

Russia's emergency situations ministry wrote on Telegram that it expected waves of up to 60 centimetres in the Commander Islands in the southwestern part of the Bering Sea, and waves of 15 to 40 centimetres in the Kamchatka peninsula.

The peninsula is the meeting point of the Pacific and North American tectonic plates, making it a seismic hot zone.

Since 1900, seven major earthquakes of magnitude 8.3 or higher have struck the area.