At least 470 earthquakes have shaken a remote island chain in southern Japan since Saturday, the Japan Meteorological Agency (JMA) reported on Thursday, June 26, urging residents to stay alert.
The seismic swarm has been concentrated around the Tokara Islands, situated south of Kyushu. By Thursday morning, the JMA had recorded 474 quakes with a seismic intensity of at least one on Japan’s seven-point scale. Though this level is generally mild—often only noticed by people who are sitting still indoors—officials warn that stronger tremors could follow.
“Seismic activity has increased,” the agency said in a statement. “This area has seen prolonged earthquake activity before, so please remain on alert for quakes that could produce strong shaking.”
The strongest quakes so far were two magnitude-5.1 events—one on Sunday, the other on Tuesday—each registering a seismic intensity of four. According to the JMA, this level of shaking can startle people, rattle dishes, and cause hanging objects to swing visibly.
A similar episode occurred in the same area in September 2023, when 346 quakes were recorded over 15 days, public broadcaster NHK reported.
The Tokara Islands consist of 12 volcanic islands, with seven inhabited by roughly 700 people. Access to the islands is limited to a ferry service that runs twice a week, depending on weather conditions.
Marine volcanology expert Hisayoshi Yokose, an associate professor at Kumamoto University, told NHK that stronger quakes remain a possibility. “An earthquake of up to magnitude 6 could take place, so please be vigilant,” he warned.
Japan, located at the intersection of four major tectonic plates within the Pacific “Ring of Fire,” is one of the most earthquake-prone nations on Earth. The country experiences around 1,500 quakes each year, making up nearly 18% of the world’s seismic activity.
While many of these earthquakes are minor, their impact can vary based on location and depth. Earlier this year, on January 1, over 400 people were killed when a powerful earthquake hit the Noto Peninsula in central Japan, causing widespread devastation during New Year celebrations.
