M4.8 Earthquake in the South Sandwich Islands region — December 4, 2024

On December 4, 2024 at 11:46 UTC, a magnitude 4.8 intermediate depth earthquake struck in the South Sandwich Islands region, at a depth of 95.2 km and coordinates -56.0523°, -27.6076°. This earthquake was detected by 23 seismic stations with excellent location accuracy and was assigned a USGS significance rating of 354, placing it among routine seismic activity.

Physical scale: An earthquake of magnitude 4.8 releases seismic energy equivalent to roughly 239 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 1.2 km — 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 5.0 mainshock that occurred 5 days ago in the South Sandwich Islands region. Since the mainshock, the USGS has recorded 0 aftershocks in this area. Aftershock activity is expected to continue for days to weeks as stresses on surrounding faults redistribute.

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