M4.4 Earthquake 14 km NE of Kuji, Japan — September 20, 2025
2025-09-20 21:47:23 UTC (2025-09-20) · approx. 6:47 AM UTC+9 local
On September 20, 2025 at 21:47 UTC, a magnitude 4.4 shallow crustal earthquake struck 14 km NE of Kuji, Japan, at a depth of 35.0 km and coordinates 40.2920°, 141.8692°.
Physical scale: An earthquake of magnitude 4.4 releases seismic energy equivalent to roughly 60 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 655 m — a useful intuition for the size of the slip patch on the fault.
This earthquake is part of an ongoing aftershock sequence following the magnitude 6.0 mainshock that occurred 17 days ago 49 km E of Noda, Japan. Since the mainshock, the USGS has recorded 8 aftershocks in this area. Aftershock activity is expected to continue for weeks to months as stresses on surrounding faults redistribute.
Earthquake Details
141.8692°E
Technical Information
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Common Questions
How strong was the magnitude 4.4 earthquake near Kuji, Japan?
The magnitude 4.4 earthquake that struck 14 km NE of Kuji, Japan on September 20, 2025 at 21:47 UTC had a depth of 35.0 km. For context, this was a light earthquake commonly felt near the epicenter.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 4.4 earthquakes can continue for several days and gradually diminish over time.
Is this the same earthquake as the M6.0 one earlier?
No. This magnitude 4.4 earthquake is an aftershock of the larger magnitude 6.0 mainshock that occurred earlier 49 km E of Noda, Japan. Aftershocks are smaller earthquakes triggered by stress changes from the mainshock.
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Understanding This Data
Magnitude 4.4 earthquakes are often felt but rarely cause damage.
Authoritative source: USGS event page (event ID: us6000rgxc). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2025, September 20, 2025). M4.4 Earthquake 14 km NE of Kuji, Japan — September 20, 2025. Retrieved December 6, 2025 from https://www.earthquaketracker.org/earthquakes/event/us6000rgxc/