M8.1 Earthquake near 2021 South Sandwich Islands Earthquake — August 12, 2021
2021-08-12 18:35:17 UTC (2021-08-12) · approx. 4:35 PM UTC-2 local
Maximum shaking intensity MMI 6.5 (very strong).
On August 12, 2021 at 18:35 UTC, a magnitude 8.1 shallow crustal earthquake struck near 2021 South Sandwich Islands Earthquake, at a depth of 22.8 km and coordinates -58.3753°, -25.2637°. The USGS PAGER system issued a green alert level for this event, indicating no significant casualties or damage expected.
Physical scale: An earthquake of magnitude 8.1 releases seismic energy equivalent to roughly 21.3 megatons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 234 km — a useful intuition for the size of the slip patch on the fault.
The epicenter is located in South Sandwich Islands, a region characterized by the South Sandwich Trench, one of Earth's most remote subduction zones.
Learn more: Magnitude scale · Aftershock sequences
ShakeMap — predicted shaking intensity
Modeled ground-motion intensity contoured on the Modified Mercalli scale (MMI). Computed by the USGS from the moment-tensor solution and regional ground-motion prediction equations.
Source: U.S. Geological Survey ShakeMap. View interactive ShakeMap on USGS
Earthquake Details
-25.2637°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 8.1 earthquake near 2021 South Sandwich Islands Earthquake?
The magnitude 8.1 earthquake that struck near 2021 South Sandwich Islands Earthquake on August 12, 2021 at 18:35 UTC had a depth of 22.8 km. For context, this was a strong earthquake capable of causing significant damage.
Where did the earthquake occur?
The earthquake epicenter was located at -58.3753°, -25.2637°, which is near 2021 South Sandwich Islands Earthquake.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 8.1 earthquakes can continue for months to years and gradually diminish over time.
Actions
Authoritative source: USGS event page (event ID: us6000f53e). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, August 12, 2021). M8.1 Earthquake near 2021 South Sandwich Islands Earthquake — August 12, 2021. Retrieved December 22, 2025 from https://www.earthquaketracker.org/earthquakes/event/us6000f53e/