A powerful earthquake has struck off the northern Japanese coast and the Japan Meteorological Agency has issued a tsunami alert in the region and warned of an increased risk of a possible mega-quake.
The Cabinet Office and the Japan Meteorological Agency said there is 1% chance of a mega-quake occurring on the northern Japanese coast in the next week or so, following the powerful quake earlier near the Chishima trough.
Officials said the advisory is not a quake prediction but urged residents to raise their preparedness, such as emergency food and their grab bag, just in case, while continuing their daily lives.
The advisory for the region is the second in recent months. One was issued following another major quake in December. No major subsequent quake occurred.
The quake, registering a preliminary magnitude of 7.4, occurred off the coast of Sanriku in northern Japan at around 4.53pm local time (0753 GMT) at a depth of about 10 kilometres (six miles) below the sea surface, the agency said.
A tsunami of about 80 centimetres (2.6ft) was detected at the Kuji port in the Iwate prefecture, and a smaller tsunami of 40 centimetres (1.3ft) 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.
Footage on NHK television showed many people driving up to parks and other facilities on higher ground.
Iwate and three other northern prefectures issued non-binding evacuation advisories to more than 128,000 residents, according to the disaster management agency.
The Fire and Disaster Management Agency said officials are assessing the situation but so far no damage or injuries have been reported, including at power stations and other facilities.
The Nuclear Regulation Authority said nuclear power plants and related facilities in the region were all intact and no abnormalities were detected.
Another powerful 7.5 magnitude quake in December left dozens injured.
It is 15 years since a magnitude 9.0 earthquake and tsunami on March 11 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 have not returned because they resettled elsewhere, their home towns remain off-limits or they have lingering concerns about radiation.