M4.3 Earthquake in the South Sandwich Islands region — April 30, 2025
2025-04-30 18:29:07 UTC (2025-04-30) · approx. 4:29 PM UTC-2 local
On April 30, 2025 at 18:29 UTC, a magnitude 4.3 shallow crustal earthquake struck in the South Sandwich Islands region, at a depth of 35.0 km and coordinates -59.7118°, -26.1223°.
Physical scale: An earthquake of magnitude 4.3 releases seismic energy equivalent to roughly 43 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 558 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 5.4 mainshock that occurred 16 days ago in the South Sandwich Islands region. Since the mainshock, the USGS has recorded 2 aftershocks in this area. Aftershock activity is expected to continue for days to weeks as stresses on surrounding faults redistribute.
Earthquake Details
-26.1223°E
Technical Information
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Common Questions
How strong was the magnitude 4.3 earthquake in the South Sandwich Islands region?
The magnitude 4.3 earthquake that struck in the South Sandwich Islands region on April 30, 2025 at 18:29 UTC had a depth of 35.0 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 4.3 earthquakes can continue for several days and gradually diminish over time.
Is this the same earthquake as the M5.4 one earlier?
No. This magnitude 4.3 earthquake is an aftershock of the larger magnitude 5.4 mainshock that occurred earlier in the South Sandwich Islands region. Aftershocks are smaller earthquakes triggered by stress changes from the mainshock.
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Understanding This Data
Magnitude 4.3 earthquakes are often felt but rarely cause damage.
Authoritative source: USGS event page (event ID: us7000pzf8). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2025, April 30, 2025). M4.3 Earthquake in the South Sandwich Islands region — April 30, 2025. Retrieved July 12, 2025 from https://www.earthquaketracker.org/earthquakes/event/us7000pzf8/