M4.3 Earthquake 99 km SSW of Urakawa, Japan — December 12, 2025
2025-12-12 23:41:42 UTC (2025-12-12) · approx. 8:41 AM UTC+9 local
On December 12, 2025 at 23:41 UTC, a magnitude 4.3 shallow crustal earthquake struck 99 km SSW of Urakawa, Japan, at a depth of 48.3 km and coordinates 41.2835°, 142.4972°.
Physical scale: An earthquake of magnitude 4.3 releases seismic energy equivalent to roughly 43 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 558 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 5.5 mainshock that occurred 29 days ago 63 km E of Mutsu, Japan. Since the mainshock, the USGS has recorded 0 aftershocks in this area. Aftershock activity is expected to continue for days to weeks as stresses on surrounding faults redistribute.
Earthquake Details
142.4972°E
Technical Information
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Common Questions
How strong was the magnitude 4.3 earthquake near Urakawa, Japan?
The magnitude 4.3 earthquake that struck 99 km SSW of Urakawa, Japan on December 12, 2025 at 23:41 UTC had a depth of 48.3 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 4.3 earthquakes can continue for several days and gradually diminish over time.
Is this the same earthquake as the M5.5 one earlier?
No. This magnitude 4.3 earthquake is an aftershock of the larger magnitude 5.5 mainshock that occurred earlier 63 km E of Mutsu, Japan. Aftershocks are smaller earthquakes triggered by stress changes from the mainshock.
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Understanding This Data
Magnitude 4.3 earthquakes are often felt but rarely cause damage.
Authoritative source: USGS event page (event ID: us7000rmz5). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2025, December 12, 2025). M4.3 Earthquake 99 km SSW of Urakawa, Japan — December 12, 2025. Retrieved March 10, 2026 from https://www.earthquaketracker.org/earthquakes/event/us7000rmz5/