M4.6 Earthquake 55 km SE of Isen, Japan — September 3, 2025
2025-09-03 20:31:16 UTC (2025-09-03) · approx. 5:31 AM UTC+9 local
On September 3, 2025 at 20:31 UTC, a magnitude 4.6 shallow crustal earthquake struck 55 km SE of Isen, Japan, at a depth of 23.2 km and coordinates 27.3882°, 129.3926°. This earthquake was detected by 64 seismic stations with excellent location accuracy and was assigned a USGS significance rating of 326, placing it among routine seismic activity.
Physical scale: An earthquake of magnitude 4.6 releases seismic energy equivalent to roughly 120 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 899 m — a useful intuition for the size of the slip patch on the fault.
The epicenter is located in Japan, a region characterized by the intersection of four tectonic plates — Pacific, Philippine Sea, Eurasian, and North American — creating multiple subduction zones. The nearest mapped fault system is the Japan Trench. View all earthquakes in Japan.
Learn more: Magnitude scale · Aftershock sequences
Earthquake Details
129.3926°E
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Common Questions
How strong was the magnitude 4.6 earthquake near Isen, Japan?
The magnitude 4.6 earthquake that struck 55 km SE of Isen, Japan on September 3, 2025 at 20:31 UTC had a depth of 23.2 km. For context, this was a light earthquake commonly felt near the epicenter.
Where did the earthquake occur?
The earthquake epicenter was located at 27.3882°, 129.3926°, which is 55 km SE of Isen, Japan. View all earthquakes in Japan.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 4.6 earthquakes can continue for several days and gradually diminish over time.
Has Japan had earthquakes this big before?
The largest recorded earthquake in Japan was the M9.1 Tohoku earthquake of March 11, 2011. Today's magnitude 4.6 event is significantly smaller than that historical record.
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Location
Authoritative source: USGS event page (event ID: us7000qtlm). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2025, September 3, 2025). M4.6 Earthquake 55 km SE of Isen, Japan — September 3, 2025. Retrieved November 30, 2025 from https://www.earthquaketracker.org/earthquakes/event/us7000qtlm/