M3.9 Earthquake 138 km N of Isabela, Puerto Rico — September 3, 2025
2025-09-03 20:48:30 UTC (2025-09-03) · approx. 4:48 PM UTC-4 local
On September 3, 2025 at 20:48 UTC, a magnitude 3.9 shallow crustal earthquake struck 138 km N of Isabela, Puerto Rico, at a depth of 40.0 km and coordinates 19.7463°, -66.9026°.
Physical scale: An earthquake of magnitude 3.9 releases seismic energy equivalent to roughly 12 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 310 m — a useful intuition for the size of the slip patch on the fault.
Earthquake Details
-66.9026°E
Technical Information
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Common Questions
How strong was the magnitude 3.9 earthquake near Isabela, Puerto Rico?
The magnitude 3.9 earthquake that struck 138 km N of Isabela, Puerto Rico on September 3, 2025 at 20:48 UTC had a depth of 40.0 km. For context, this was a minor earthquake typically detected only by instruments.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 3.9 earthquakes can continue for several days and gradually diminish over time.
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Understanding This Data
Magnitude 3.9 earthquakes are typically only recorded by instruments.
Authoritative source: USGS event page (event ID: pr2025246004). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2025, September 3, 2025). M3.9 Earthquake 138 km N of Isabela, Puerto Rico — September 3, 2025. Retrieved November 30, 2025 from https://www.earthquaketracker.org/earthquakes/event/pr2025246004/