Japan Gov't Warns of Possible Megaquake

Apr 20, 2026 | News On Japan

HOKKAIDO, Apr 20, 2026 (News On Japan) - Japan's weather agency and the Cabinet Office issued a 'Hokkaido-Sanriku Offshore Subsequent Earthquake Advisory' after an earthquake measuring upper 5 on Japan's seismic intensity scale struck off Sanriku.

The earthquake occurred at around 4:52 p.m. on April 20 off the coast of Sanriku, with Aomori Prefecture recording the strongest shaking at upper 5 intensity.

Following the quake, the Japan Meteorological Agency temporarily issued tsunami warnings for Iwate Prefecture, the Pacific coast of Aomori Prefecture, and the central Pacific coast of Hokkaido.

At Kuji Port in Iwate Prefecture, an 80-centimeter tsunami was observed at 5:34 p.m. Tide levels continued to fluctuate afterward, while tsunami waves measuring several tens of centimeters were also recorded at other coastal locations in the prefecture.

In Rikuzentakata, Iwate Prefecture, an area heavily damaged in the Great East Japan Earthquake of March 2011, residents were seen evacuating to higher ground under the guidance of employees at a commercial facility.

One evacuee said, 'My heart was pounding as everyone helped me climb up to this park. I think we're safe now, but it's still a little frightening.'

Yugo Masutani, planning official at the Cabinet Office's disaster management division, said there is around a 1% chance of a large-scale earthquake of magnitude 8 or higher occurring within the next week.

The advisory, issued on the night of April 20, warns that the likelihood of a new megaquake of magnitude 8 class or above occurring on the seabed of the Pacific Ocean -- from off Nemuro in Hokkaido to off Sanriku in northeastern Japan -- is higher than usual.

The advisory covers seven prefectures and regions: Hokkaido, Aomori, Iwate, Miyagi, Fukushima, Ibaraki and Chiba.

The Japan Meteorological Agency and the Cabinet Office urged residents to review earthquake preparedness measures and follow disaster-response guidance issued by the central government and local authorities.

Meanwhile, tsunami warnings that had been in place were downgraded to tsunami advisories for all affected areas.

Separately, an elderly man in his 80s fell in Morioka City during the earthquake and injured his left leg. Authorities said his injuries were not life-threatening.

Source: TBS

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