7.5-magnitude quake off Sanriku coast prompts tsunami warnings; 80cm wave recorded at Kuji

Mon, 20 Apr 2026 10:27:02 +0000
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by Elena Vance -

Major 7.5-magnitude earthquake off northeastern Japan prompts tsunami warnings

Tokyo — A strong earthquake with a preliminary magnitude of about 7.5 struck off Japan’s northeastern Sanriku coast on April 20, 2026, the Japan Meteorological Agency said, prompting the agency to issue tsunami warnings and advisories for parts of Iwate, Aomori and Hokkaido.

The JMA said the quake originated in waters off Sanriku in Iwate Prefecture at about 4:53 p.m. local time and was shallow, with an estimated depth of roughly 10 kilometres.

Initial JMA warnings said tsunami waves as high as about 3 metres (10 feet) were possible along some stretches of coast. Coastal tide gauges later recorded tsunami activity at Japanese ports, including a wave of about 80 centimetres at Kuji port in Iwate and smaller waves at other ports.

Japan’s Meteorological Agency is the country’s official authority for earthquake and tsunami warnings and typically issues tsunami warnings and advisories within minutes of offshore events; the rapid alerts on April 20 reflected that practice.