Japan gives first megaquake warning after latest tremor

Authorities urge coast dwellers to stay vigilant as 'megathrust quake' could trigger tsunami that kills hundreds of thousands

- ALEX CROFT

Japan's weather agency has issued a megaquake warning, the highest level of earthquake alert, hours after a 7.5 magnitude tremor struck the country.

Residents living near the Pacific coast have been urged by authorities to remain vigilant throughout the coming week and prepare evacuation plans in case they need to flee their homes.

At least 33 people were injured in the earthquake in Aomori prefecture on the main island of Honshu on Monday night, with waves reaching up to 70cm seen in several coastal communities.

Tsunami alerts have been lifted, but a megaquake notice revives the threat of large and devastating tsunamis along Japan's Pacific coast, authorities warned.

Yesterday's announcement was the first time this top-tier alert has been issued since the early warning system was launched in 2022.

A megaquake, also known as a megathrust earthquake, is an extremely powerful earthquake with a magnitude above 8.0 on the Richter scale, according to Japan's Headquarters for Earthquake Research Promotion.