A powerful undersea earthquake off Japan’s northeastern coast has triggered tsunami warnings across three prefectures, as a series of significant tremors continues to rattle the Pacific region.
The ground shook across northern Japan on Monday afternoon when a 7.5-magnitude earthquake struck in off the coast of Iwate prefecture, sending tremors strong enough to reach Tokyo, hundreds of kilometres to the south. The Japan Meteorological Agency issued an immediate tsunami warning, cautioning residents in Iwate, Aomori and Hokkaido prefectures to brace for waves of up to three metres.
What We Know About Monday’s Japan Earthquake
The at 4:53 pm local time, with its epicentre located in the Pacific Ocean at a depth of 10 kilometres, according to the Japan Meteorological Agency. It registered an upper 5 on Japan’s seismic intensity scale — a threshold at which movement becomes difficult without support and unreinforced concrete-block walls are liable to collapse. Large buildings as far away as Tokyo reported noticeable shaking.
Authorities moved swiftly to issue for coastal communities across the three affected prefectures, urging residents to move to higher ground.
A Week of Seismic Activity Across the Pacific Region
Monday’s earthquake in Japan is the most powerful in a string of significant seismic events to strike the broader Pacific region over the past week.
On 18 April, a magnitude 5.0 earthquake struck the mountainous Nagano prefecture in central Japan, hitting the Omachi area in northern Nagano at around 1:20 pm local time. It too registered an upper 5 on Japan’s seismic intensity scale. No immediate damage was reported.
A day later, on 19 April, a magnitude 6.1 earthquake struck the Hihifo region of Tonga, according to the US Geological Survey. On the same day, a 5.9-magnitude tremor hit western Indonesia, with the country’s Meteorology, Climatology and Geophysics Agency reporting the epicentre 48 kilometres northwest of the Nias area off Sumatra island, at a depth of 10 kilometres.
Earlier in the month, on 12 April, a magnitude 4.9 earthquake was recorded in the Indian Ocean, according to India’s National Centre of Seismology. “EQ of M: 4.9, On: 12/04/2026 08:10:38 IST, Lat: 1.806 N, Long: 94.924 E, Depth: 10 Km, Location: Indian Ocean,” the agency said in a post on X.
Why Japan Is So Vulnerable to Earthquakes and Tsunamis
Japan sits at the intersection of several tectonic plates and is one of the most seismically active countries on earth. The nation accounts for roughly one-fifth of all earthquakes globally measuring magnitude 6 or greater — a statistic that underpins the country’s world-leading investment in earthquake-resistant infrastructure and early warning systems.
Indonesia, similarly, lies along the Pacific Ring of Fire, where the collision of multiple tectonic plates produces recurrent volcanic and seismic activity, making it one of the most earthquake-prone nations in the world.
Monday’s events serve as a reminder that for the communities living along the Pacific’s seismic fault lines, the threat of the next earthquake is never far away.
