Tokyo, 20 April 

A powerful earthquake struck off the northern Japanese coast, and the Japan Meteorological Agency issued a tsunami alert in the region.

The quake, registering a preliminary magnitude of 7.5, occurred off the coast of Sanriku in northern Japan at around 4:53pm (0753 GMT), at a depth of about 10 kilometres (6 miles) below the sea surface, the agency said.

A tsunami of about 80 centimetres (2.6 feet) was detected at the Kuji port in the Iwate prefecture, and a smaller tsunami of 40 centimetres (1.3 feet) was recorded at another port in the prefecture, the agency said.

The agency urged residents in the region to immediately stay away from the coast or along rivers and take shelter on higher ground. It also cautioned people in the area against possible aftershocks for about a week.

The Iwate prefecture issued non-binding evacuationadvisories to residents in 11 towns.

A tsunami of up to 3 metres (10 feet) could hit the area, the agency said. In addition to the tsunami alert in Iwate and Aomori to the north and southeastern Hokkaido, the agency also issued a milder tsunami advisory for the coasts of Miyagi and Fukushima, south of the epicentre.

Another 7.5 magnitude quake in December left dozens injured.

It's been 15 years since a magnitude 9.0 earthquake andtsunami on 11 March, 2011, ravaged parts of northern Japan, caused more than 22,000 deaths and forced nearly half a million people to flee their homes, most of them due to tsunami damage.

Some 160,000 people fled their homes in Fukushima because of the radiation spewed from the tsunami-hit Fukushima Daiichi nuclear power plant. About 26,000 of them haven't returned because they resettled elsewhere, their hometowns remain off-limits, or they have lingering concerns about radiation.