M3.9 Earthquake 152 km NE of Cruz Bay, U.S. Virgin Islands — September 20, 2021
2021-09-20 23:44:59 UTC (2021-09-20) · approx. 7:44 PM UTC-4 local
On September 20, 2021 at 23:44 UTC, a magnitude 3.9 intermediate depth earthquake struck 152 km NE of Cruz Bay, U.S. Virgin Islands, at a depth of 120.0 km and coordinates 19.3805°, -63.8518°.
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
-63.8518°E
Technical Information
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Common Questions
How strong was the magnitude 3.9 earthquake near Cruz Bay, U.S. Virgin Islands?
The magnitude 3.9 earthquake that struck 152 km NE of Cruz Bay, U.S. Virgin Islands on September 20, 2021 at 23:44 UTC had a depth of 120.0 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: pr2021263007). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, September 20, 2021). M3.9 Earthquake 152 km NE of Cruz Bay, U.S. Virgin Islands — September 20, 2021. Retrieved September 21, 2021 from https://www.earthquaketracker.org/earthquakes/event/pr2021263007/