The first tsunami wave reached 80 centimeters at Kuji Port in Iwate prefecture shortly after a 7.5-magnitude earthquake struck off Japan’s northeastern coast on April 20, 2026.
The quake, centered offshore near Aomori, triggered immediate tsunami warnings across northern Japan, with advisories issued for Iwate, Aomori, and Hokkaido prefectures. Residents in coastal areas were urged to evacuate to higher ground as authorities monitored for potentially larger follow-on waves.
Japan issues urgent evacuation orders as tsunami threat persists
Japanese broadcaster NHK reported that while the initial wave was relatively modest, officials warned that second and third tsunami surges could be higher and more dangerous. Evacuation centers opened in affected towns, and emergency sirens sounded along the coast as a precaution.
No casualties or major damage have been confirmed in the immediate aftermath, but search and rescue teams remain on standby. The Japan Meteorological Agency continues to monitor seismic and sea-level activity, updating warnings in real time.
Historical context shapes Japan’s cautious response to undersea quakes
Japan experiences a magnitude 7.0 or greater earthquake roughly every 16 months, with the most recent prior event being a 7.6-magnitude quake off Aomori in December 2025. That tremor also prompted tsunami advisories but resulted in minimal impact.
The deadly 2011 Tohoku earthquake, measuring 9.0, remains the benchmark for disaster preparedness; it generated waves over 10 meters high, killed more than 18,000 people, and caused the Fukushima nuclear crisis. Since then, public education has emphasized that even small tsunami waves can be lethal due to strong currents, and debris.
How high can tsunami waves grow after the initial surge?
According to NHK and the Japan Meteorological Agency, later tsunami waves can exceed the height of the first, particularly in narrow bays or river estuaries where water funnels and amplifies.
Are nuclear facilities at risk from this earthquake?
There is no mention in the sources of any threat to nuclear plants; the quake’s epicenter was offshore north of Fukushima, and no alerts were issued for facilities in the region.
