M4.8 Earthquake 81 km S of Koshima, Japan — September 9, 2025
2025-09-09 20:56:17 UTC (2025-09-09) · approx. 5:56 AM UTC+9 local
On September 9, 2025 at 20:56 UTC, a magnitude 4.8 shallow crustal earthquake struck 81 km S of Koshima, Japan, at a depth of 35.0 km and coordinates 29.5040°, 130.5768°. This earthquake was detected by 119 seismic stations with good location accuracy and was assigned a USGS significance rating of 354, placing it among routine seismic activity.
Physical scale: An earthquake of magnitude 4.8 releases seismic energy equivalent to roughly 239 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 1.2 km — 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
130.5768°E
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Common Questions
How strong was the magnitude 4.8 earthquake near Koshima, Japan?
The magnitude 4.8 earthquake that struck 81 km S of Koshima, Japan on September 9, 2025 at 20:56 UTC had a depth of 35.0 km. For context, this was a light earthquake commonly felt near the epicenter.
Where did the earthquake occur?
The earthquake epicenter was located at 29.5040°, 130.5768°, which is 81 km S of Koshima, Japan. View all earthquakes in Japan.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 4.8 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 4.8 event is significantly smaller than that historical record.
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Location
Authoritative source: USGS event page (event ID: us7000qv4u). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2025, September 9, 2025). M4.8 Earthquake 81 km S of Koshima, Japan — September 9, 2025. Retrieved November 30, 2025 from https://www.earthquaketracker.org/earthquakes/event/us7000qv4u/