Tokyo, December 09: Japan was hit by a massive 7.6 magnitude earthquake on Monday, December 8, prompting the officials at the Japan Meteorological Agency (JMA) to issue a “megaquake” warning. According to the officials, a “megaquake” could occur along Japan’s main island's north coast in the coming week after the 7.6-magnitude tremor shook the same region on December 08.

On December 08, a mammoth 7.6-magnitude earthquake struck off northern Japan on Monday, 8 December. The powerful earthquake prompted a tsunami alert, with waves as high as 10 feet expected across the northeastern coast, according to the JMA. The quake hit off the coast of Hokkaido near Aomori, with its epicentre about 50 km (30 miles) below the seabed. Earthquake in Japan: Magnitude 7.6 Quake Hits Island Nation, Tsunami Warning Issued.

What Is Megaquake?

A megaquake is an extremely powerful earthquake that measures magnitude 8.0 or greater. Such an earthquake could trigger massive tsunami waves and destroy infrastructure on a large scale. It was the first time Japan issued a top-tier alert since the launch of a warning system in 2022. This system was put in place to detect the likelihood of a big one hitting the country.

Japan Issues Megaquake Warning a Day After Massive 7.6 Magnitude Earthquake

Japan’s disaster agency has issued its first-ever megaquake warning for the coastal regions of Hokkaido and Sanriku since the early warning system’s launch in December 2022, local paper Asahi reported. At a press conference on Tuesday, December 09, Tsukasa Morikubo, a Cabinet official for disaster management, warned that a massive earthquake could strike along the Japan Trench and Kuril Trench near Hokkaido, potentially following December 08's tremor. Earthquake in Japan Videos: Homes Shake, Lights Swing As Powerful 7.6 Magnitude Quake Hits Japan, Triggers Tsunami Warning.

Japan's Earthquake Warning System

Japan’s Earthquake Early Warning system, operated by the Japan Meteorological Agency (JMA) since around 2007, alerts residents immediately as quakes begin, estimating their intensity and arrival time. This system was updated in December 2022 by the Headquarters for Earthquake Research Promotion (HERP) and the JMA. It has a Japanese name, which in English roughly translates to "Hokkaido–Sanriku-offshore Aftershock Earthquake Alert Information".

But even with one of the world’s most advanced warning networks, the risk and anxiety that come with it are non-negligible. Sitting on the Ring of Fire, Japan experiences tremors every few minutes, most too small to notice, keeping fears of a devastating “Big One” alive.

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(The above story first appeared on LatestLY on Dec 09, 2025 04:39 PM IST. For more news and updates on politics, world, sports, entertainment and lifestyle, log on to our website latestly.com).