M4.1 Earthquake 78 km SW of San Antonio, Chile — April 28, 2021
2021-04-28 21:50:07 UTC (2021-04-28) · approx. 4:50 PM UTC-5 local
On April 28, 2021 at 21:50 UTC, a magnitude 4.1 shallow crustal earthquake struck 78 km SW of San Antonio, Chile, at a depth of 23.3 km and coordinates -34.0061°, -72.2952°.
Physical scale: An earthquake of magnitude 4.1 releases seismic energy equivalent to roughly 21 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 406 m — a useful intuition for the size of the slip patch on the fault.
This earthquake is part of an ongoing aftershock sequence following the magnitude 5.2 mainshock that occurred 3 days ago 62 km SW of San Antonio, Chile. Since the mainshock, the USGS has recorded 1 aftershocks in this area. Aftershock activity is expected to continue for days to weeks as stresses on surrounding faults redistribute.
Earthquake Details
-72.2952°E
Technical Information
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Common Questions
How strong was the magnitude 4.1 earthquake near San Antonio, Chile?
The magnitude 4.1 earthquake that struck 78 km SW of San Antonio, Chile on April 28, 2021 at 21:50 UTC had a depth of 23.3 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 4.1 earthquakes can continue for several days and gradually diminish over time.
Is this the same earthquake as the M5.2 one earlier?
No. This magnitude 4.1 earthquake is an aftershock of the larger magnitude 5.2 mainshock that occurred earlier 62 km SW of San Antonio, Chile. Aftershocks are smaller earthquakes triggered by stress changes from the mainshock.
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Understanding This Data
Magnitude 4.1 earthquakes are often felt but rarely cause damage.
Authoritative source: USGS event page (event ID: us7000dycs). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, April 28, 2021). M4.1 Earthquake 78 km SW of San Antonio, Chile — April 28, 2021. Retrieved July 7, 2021 from https://www.earthquaketracker.org/earthquakes/event/us7000dycs/