M3.3 Earthquake 43 km NW of San Antonio, Puerto Rico — December 29, 2021
2021-12-29 22:31:25 UTC (2021-12-29) · approx. 6:31 PM UTC-4 local
On December 29, 2021 at 22:31 UTC, a magnitude 3.3 shallow crustal earthquake struck 43 km NW of San Antonio, Puerto Rico, at a depth of 8.0 km and coordinates 18.8018°, -67.3475°.
Physical scale: An earthquake of magnitude 3.3 releases seismic energy equivalent to roughly 1.2 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 107 m — a useful intuition for the size of the slip patch on the fault.
Earthquake Details
-67.3475°E
Technical Information
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Common Questions
How strong was the magnitude 3.3 earthquake near San Antonio, Puerto Rico?
The magnitude 3.3 earthquake that struck 43 km NW of San Antonio, Puerto Rico on December 29, 2021 at 22:31 UTC had a depth of 8.0 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 3.3 earthquakes can continue for several days and gradually diminish over time.
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Understanding This Data
Magnitude 3.3 earthquakes are typically only recorded by instruments.
Authoritative source: USGS event page (event ID: pr2021363004). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, December 29, 2021). M3.3 Earthquake 43 km NW of San Antonio, Puerto Rico — December 29, 2021. Retrieved December 29, 2021 from https://www.earthquaketracker.org/earthquakes/event/pr2021363004/