M3.4 Earthquake 54 km NNW of San Antonio, Puerto Rico — September 27, 2025
2025-09-27 16:01:05 UTC (2025-09-27) · approx. 12:01 PM UTC-4 local
On September 27, 2025 at 16:01 UTC, a magnitude 3.4 shallow crustal earthquake struck 54 km NNW of San Antonio, Puerto Rico, at a depth of 6.2 km and coordinates 18.9333°, -67.3382°.
Physical scale: An earthquake of magnitude 3.4 releases seismic energy equivalent to roughly 1.9 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 134 m — a useful intuition for the size of the slip patch on the fault.
Earthquake Details
-67.3382°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 3.4 earthquake near San Antonio, Puerto Rico?
The magnitude 3.4 earthquake that struck 54 km NNW of San Antonio, Puerto Rico on September 27, 2025 at 16:01 UTC had a depth of 6.2 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 3.4 earthquakes can continue for several days and gradually diminish over time.
What should I do after an earthquake?
If you were in the affected area: check yourself and others for injuries, inspect your home for damage, and be prepared for aftershocks. For detailed guidance, see our earthquake safety guide and emergency planning resources.
Actions
Understanding This Data
Magnitude 3.4 earthquakes are typically only recorded by instruments.
Authoritative source: USGS event page (event ID: pr71496623). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2025, September 27, 2025). M3.4 Earthquake 54 km NNW of San Antonio, Puerto Rico — September 27, 2025. Retrieved May 28, 2026 from https://www.earthquaketracker.org/earthquakes/event/pr71496623/