M4.3 Earthquake in the Bonin Islands, Japan region — August 21, 2025
2025-08-21 18:51:23 UTC (2025-08-21) · approx. 3:51 AM UTC+9 local
On August 21, 2025 at 18:51 UTC, a magnitude 4.3 deep-focus earthquake struck in the Bonin Islands, Japan region, at a depth of 511.3 km and coordinates 28.0083°, 139.3748°.
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.
Earthquake Details
139.3748°E
Technical Information
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Common Questions
How strong was the magnitude 4.3 earthquake in the Bonin Islands, Japan region?
The magnitude 4.3 earthquake that struck in the Bonin Islands, Japan region on August 21, 2025 at 18:51 UTC had a depth of 511.3 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.
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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: us6000r2tq). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2025, August 21, 2025). M4.3 Earthquake in the Bonin Islands, Japan region — August 21, 2025. Retrieved November 12, 2025 from https://www.earthquaketracker.org/earthquakes/event/us6000r2tq/