M4.9 Earthquake 28 km ESE of San Martín, Argentina — September 29, 2021
2021-09-29 07:53:56 UTC (2021-09-29) · approx. 2:53 AM UTC-5 local
Felt by 31 people across nearby locations.
On September 29, 2021 at 07:53 UTC, a magnitude 4.9 shallow crustal earthquake struck 28 km ESE of San Martín, Argentina, at a depth of 10.0 km and coordinates -33.1693°, -68.1801°.
Physical scale: An earthquake of magnitude 4.9 releases seismic energy equivalent to roughly 338 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 1.4 km — a useful intuition for the size of the slip patch on the fault.
Did You Feel It? — community-reported shaking
Aggregated felt-report intensity from 31 citizen responses to the USGS Did You Feel It? system. Each colored zone represents the average MMI from reports in that area.
Source: U.S. Geological Survey Did You Feel It?. View on USGS · submit your own report
Earthquake Details
-68.1801°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 4.9 earthquake near San Martín, Argentina?
The magnitude 4.9 earthquake that struck 28 km ESE of San Martín, Argentina on September 29, 2021 at 07:53 UTC had a depth of 10.0 km. For context, this was a light earthquake commonly felt near the epicenter.
Where did the earthquake occur?
The earthquake epicenter was located at -33.1693°, -68.1801°, which is 28 km ESE of San Martín, Argentina.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 4.9 earthquakes can continue for several days and gradually diminish over time.
Authoritative source: USGS event page (event ID: us6000fq1z). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, September 29, 2021). M4.9 Earthquake 28 km ESE of San Martín, Argentina — September 29, 2021. Retrieved December 22, 2025 from https://www.earthquaketracker.org/earthquakes/event/us6000fq1z/