Shallow M5.5 earthquake hits South Sandwich Islands region
A M5.5 earthquake was recorded at 13:08 UTC on October 11, 2025, in the South Sandwich Islands region. The event originated at a depth of 54.7 km (34 miles), with the epicenter located at coordinates 26.6°S, 56.4°W.
The South Sandwich Islands are a remote chain in the southern Atlantic Ocean, far from populated landmasses. The epicentral coordinates place this event solidly offshore, in the vicinity of the sub-Antarctic island arc.
Given the region’s remote and oceanic nature, the primary infrastructure near the epicenter would be limited to navigational sea routes or occasional scientific/research expeditions, with no significant urban, energy, or transport infrastructure present.
There is no tsunami threat associated with this earthquake, based on its location and available data.
USGS issued a green alert for this event, indicating a low likelihood of casualties or damage.
The maximum estimated intensity is IV. The significance index is 465 (on a scale that runs through 1 000), based on magnitude, felt reports, and estimated impact.
The South Sandwich Islands region lies along the South Sandwich Trench, an active subduction zone where the South American Plate descends beneath the small South Sandwich Plate. This tectonic setting frequently produces moderate to strong seismic events.
This information was last updated at 13:30 UTC on October 11, 2025.