An earthquake swarm in the Tokara Islands, southern Japan, has produced 474 tremors since June 21, 2025, with events reaching magnitudes up to M5.1 and a maximum local Japanese Shinto intensity of 4.
An earthquake swarm that began on June 21, in the volcanic chain of Tokara Islands in Kagoshima Prefecture, southern Japan has triggered hundreds of tremors over several days. By the morning of June 26, the Japan Meteorological Agency (JMA) had recorded at least 474 quakes, including several above M3.5 and others strong enough to reach a seismic intensity of 4.
According to JMA data, the strongest events so far have been in the M5.0–5.1 range, with depths generally around 10–20 km (6-12 miles). Shaking has been widely felt across Toshima village and nearby islands, though no major damage or injuries have been reported.
The JMA has warned residents to remain vigilant, noting the possibility of a more powerful earthquake.
Daily seismic bulletins confirm a sustained pattern of low- to moderate-magnitude events concentrated south of Yakushima Island. This is a seismically active region where tectonic interaction between the Philippine Sea Plate and the Eurasian Plate happens.
Seismic intensity distribution data from JMA’s real-time network show localized Shindo readings of 2-4 across the affected regions, such as Toshima Village and its surrounding areas. These intensities are noticeable indoors but rarely damaging.
The Tokara Islands are part of the Ryukyu Arc, a zone historically prone to both earthquake swarms and volcanic activity. Most swarms fade out quietly, but cases like the 2000 Izu Islands show they can sometimes lead to stronger quakes over time.
As of June 26, the JMA has not issued any tsunami warnings or special volcanic bulletins for the region.
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