M4.7 Earthquake 6 km W of Onna, Japan — August 21, 2026
2026-08-21 00:01:20 UTC (3 hours ago) · approx. 9:01 AM UTC+9 local
On August 21, 2026 at 00:01 UTC, a magnitude 4.7 shallow crustal earthquake struck 6 km W of Onna, Japan, at a depth of 44.1 km and coordinates 26.4848°, 127.7859°. This earthquake was detected by 41 seismic stations with excellent location accuracy and was assigned a USGS significance rating of 340, placing it among routine seismic activity.
Physical scale: An earthquake of magnitude 4.7 releases seismic energy equivalent to roughly 169 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 1.1 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
127.7859°E
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Common Questions
How strong was the magnitude 4.7 earthquake near Onna, Japan?
The magnitude 4.7 earthquake that struck 6 km W of Onna, Japan on August 21, 2026 at 00:01 UTC had a depth of 44.1 km. For context, this was a light earthquake commonly felt near the epicenter.
Where did the earthquake occur?
The earthquake epicenter was located at 26.4848°, 127.7859°, which is 6 km W of Onna, Japan. View all earthquakes in Japan.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 4.7 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 4.7 event is significantly smaller than that historical record.
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Location
Authoritative source: USGS event page (event ID: us6000tmc4). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2026, August 21, 2026). M4.7 Earthquake 6 km W of Onna, Japan — August 21, 2026. Retrieved August 21, 2026 from https://www.earthquaketracker.org/earthquakes/event/us6000tmc4/