A tsunami wave of 80-centimetre hit a port in northern Japan on Monday following powerful magnitude 7.5 earthquake struck the region, Japan’s Meteorological Agency (JMA) said.
The agency had earlier earlier issued a tsunami warning for coastal areas in the region. Earlier, a smaller 40-centimetre tsunami had struck at another port in the prefecture, followed by a 70-centimetre wave, news agency AFP reported.
The quake hit in offshore waters, triggering emergency alerts as officials warned of potentially dangerous waves along parts of Japan’s northeastern coastline.
Initial reports indicated strong tremors were felt across several prefectures, though there were no immediate details on casualties or damage. Authorities continued to monitor sea levels and seismic activity following the quake.
Meteorological Agency warns larger tsunami waves could follow
The Japan Meteorological Agency has confirmed that a 7.5-magnitude earthquake struck off the coast of Sanriku at 16:52 (08:52 BST) local time and had a depth of 10km (6.2 miles).
At a press briefing, the Japan Meteorological Agency also warned that larger tsunami waves could follow the initial surge. Tsunami alerts have been issued for parts of Hokkaido and Iwate Prefecture, with authorities urging residents in coastal areas to remain on high alert.
Frequency of earthquakes in Japan
Japan experiences powerful earthquakes with notable frequency, with magnitude 7 or higher quakes occurring roughly once every 16 months on average. According to the Japan Meteorological Agency, the country accounts for over 10% of the world’s earthquakes measuring magnitude 6 or above.
Before this, the last major tremor was a magnitude 7.6 quake off Aomori Prefecture in December 2025. However, the deadliest disaster in recent history remains the 2011 Tohoku earthquake and tsunami, a magnitude 9.0 event that triggered massive tsunami waves, claimed more than 18,000 lives, and led to a nuclear meltdown in Fukushima Prefecture. During that disaster, many residents underestimated the scale of the tsunami and failed to evacuate to higher ground in time. In response, authorities have since strengthened warning systems and emergency messaging, urging immediate evacuation when alerts are issued. Public awareness has also improved significantly since 2011, with education campaigns highlighting that even tsunami waves as small as 30 centimetres can pose a serious threat to life.
Japan’s three-tier system for tsunami warnings:
Major Tsunami Warning: Waves exceeding 3 metres are expected. Immediate evacuation of coastal areas is critical, with severe damage likely to buildings near the shoreline.
Tsunami Warning: Waves of up to 3 metres are forecast. Authorities order evacuations, and damage to low-lying structures is anticipated.
Tsunami Advisory: Waves of up to 1 metre are expected. People in the water face danger and are advised to leave the sea immediately.