Russia, North Korea, South Korea on tsunami alert after massive Japan quake

Russia and North Korea are on alert for potential tsunamis after a major 7.5 magnitude earthquake rocks Japan, sending the first tsunami waves to South Korea's east coast.

Emergency services in Russia's Sakhalin island near Japan declared a "tsunami alert" on Monday, saying the island's western coast "may be affected by tsunami waves."

Russian authorities in the Pacific city of Vladivostok also announced an alert and ordered fishermen to "urgently get back to shore."

Meanwhile, North Korea issued tsunami warnings for its east coast, saying waves of up to 2.08 metres (6.8 ft) can reach its shore, Yonhap news reported citing the North's state radio.

Earlier, the Japan Meteorological Agency reported several quakes off the coast of Ishikawa and nearby prefectures. One of the most powerful quakes had a magnitude of 7.5, according to USGS.

In response, Japan issued a major tsunami warning for Ishikawa and lower-level tsunami warnings or advisories for the rest of the western coast of the island of Honshu.

First tsunami reaches South Korea

Japanese public broadcaster NHK TV warned torrents of water could reach as high as 5 metres (16.5 feet) and urged people to flee to high land or the top of a nearby building as quickly as possible.

The first tsunami reached South Korea's east coast at 0921 GMT at a height of 45 centimetres (1.5 ft), South Korea's meteorological agency said.

The tsunami can grow after the initial waves and may continue for more than 24 hours, the agency said in an advisory.

It said tsunami waves of up to 0.3 metres could reach South Korea's eastern shore between 0929 GMT and 1017 GMT.

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