Japan's Meteorological Agency issued a tsunami warning of up to three metres for Pacific coastal areas of Hokkaido and the Tohoku region after a magnitude 7.4 earthquake struck off the Sanriku coast on April 20, the Asahi Shimbun reported.

The quake struck at 16:53 local time at a depth of around 10km, with the epicentre off the Sanriku coast in the Pacific Ocean - one of the world's most active earthquake regions.

The maximum recorded intensity was lower 6 on Japan's seven-point shindo scale, registered in the town of Hashikami in Aomori Prefecture.

Upper 5 readings were recorded across multiple towns and cities in Aomori, Iwate and Miyagi prefectures, including Hachinohe, Morioka, Ninohe, Hanamaki and Tome.

Lower 5 readings spanned a wide area of Iwate, Miyagi and Aomori, with shindo 4 readings as far afield as Hokkaido and Yamagata. Tremors were felt across a wide area, with shindo 3 reports reaching as far south as Tokyo, Kanagawa, Saitama and Chiba prefectures.

A press conference held soon afterwards by Prime Minister Sanae Takaichi said reports of damage and casualties were being investigated.

This was followed by Japan's Meteorological Agency announcing that in the weeks following the quake, there may be large-scale aftershocks.

The Sanriku coast, which faces the Pacific Ocean off Japan's northeastern coast, was severely affected by the March 11, 2011 Great East Japan Earthquake and tsunami that killed more than 18,000 people and triggered the Fukushima Daiichi nuclear disaster. Thousands are still missing.