Shallow M5.6 earthquake hits south of Yonakuni, Japan

A shallow M5.6 earthquake struck at 05:00 UTC on September 30, 2026, approximately 74 km (46 miles) south of Yonakuni, Japan. The earthquake originated at a depth of 10.8 km (6.7 miles), according to data reviewed by the USGS.

The epicenter was located at coordinates 23.8°N, 122.9°E, placing it offshore in the East China Sea, south of Japan’s westernmost island of Yonakuni. The area is characterized by its proximity to the Ryukyu Island chain and relative isolation from major population centers.

Given the offshore setting near Yonakuni Island, maritime infrastructure such as ports and regional shipping routes may be present in the broader area, along with small island airstrips and navigation facilities. Larger critical infrastructure is limited due to the region’s remoteness.

There is no tsunami threat associated with this earthquake, based on its location and available data.

One felt report was registered for this event. The significance index for this earthquake is 483 (on a scale that runs through 1 000), based on magnitude, felt reports, and estimated impact.

The region surrounding Yonakuni features complex tectonics at the convergent boundary between the Philippine Sea Plate and the Eurasian Plate, resulting in frequent seismic activity along the Ryukyu Trench and island arc system.

This information was last updated at 05:16 UTC on September 30, 2026.