A tsunami measuring under one metre (3.3 ft) reached South Korea’s east coast in the wake of a massive earthquake that hit Japan on Monday, South Korea’s meteorological agency said, which added there may be more and larger waves in the next hours.

The first tsunami to reach South Korea’s coast was 67 cm (2.2 ft) but it may increase in size after the initial waves and may continue for more than 24 hours, the meteorological agency said

An earthquake with a preliminary magnitude of 7.6 hit north central Japan on Monday, public broadcaster NHK said. The Japan Meteorological Agency issued a tsunami warning along the western coastal regions of Ishikawa, Niigata, and Toyama prefectures.

Separately, North Korea issued tsunami warnings for its coast of possible waves of more than 2 metres, South Korea’s Yonhap news agency reported, citing the North’s state radio.

South Korea’s Gangwon province warned residents to take precautions and evacuate to higher ground, according to the Ministry of Interior and Safety.

The east coast province told residents in emergency messages to stay away from the coast and evacuate to higher ground. The city of Samcheok advised residents to move to areas higher than a three-storey building, the ministry said.

Soon after the quake, reports from the region suggested massive destruction in a large area. Videos posted to social media platforms show cracks in roads and some of the houses damaged beyond repairs.

There was no official word on the extent of destruction immediately as officials focused on evacuation from the coastal region.

Tsunami of up to 5 metres high were believed to be reaching Noto in Ishikawa Prefecture, according to the weather agency.

Waves more than 1 metre high hit the coast of Wajima City in Ishikawa Prefecture, NHK reported.

Hokuriku Electric Power said it is checking for any irregularities at its nuclear power plants, NHK reported.

Nuclear reactors in the region

The region houses several nuclear reactors and there were fears of a nuclear disaster. Japan’s Fukushima nuclear reactor was damaged in a similar earthquake in 2011.

However, the government said that no abnormalities have been reported so far, new agency AFP reported.

“It has been confirmed that there are no abnormalities at Shika nuclear power plant (in Ishikawa) and other stations as of now,” government spokesman Yoshimasa Hayashi said.

Russia declares tsunami warnings: Agencies

Parts of Sakhalin island’s western coast and the mainland Primorsk and Khabarovsk regions, which are situated close to Japan on Russia’s Pacific seaboard, are under threat of tsunami, state news agency TASS reported on Monday, citing officials.

A massive earthquake with a preliminary magnitude of 7.6 struck central Japan on Monday, triggering a tsunami warning and advisories for residents to evacuate.

Russian media cited authorities in the Primorsk region port city of Vladivostok as saying that anyone sailing in local waters should “urgently return to the shore”.

TASS cited authorities in Sakhalin and Khabarovsk regions as saying that the wave would not be life-threatening.

It also quoted Russia’s emergencies ministries as denying earlier reports that an evacuation of the population of at-risk areas on Sakhalin was underway.