M5.1 earthquake – South Sandwich Islands Region
A magnitude 5.1 earthquake struck in the South Sandwich Islands region at 03:43 UTC on 28 Sept 2026, at a depth of 35 km, according to USGS and GFZ.
Reported by 2 agencies · revised from M5.3
Data: USGS, GFZ · updated 2026-09-28 03:57 UTC · reviewed
- Magnitude
- 5.1moderate
body-wave magnitude (mb)
revised from 5.3 - Depth
- 35 km
- Status
- Reviewed
- Origin time
- 2026-09-28 03:43:44 UTC
- Epicentre
- 57.670° S, 25.279° W
Circles show this event and others within 45 km from 7 days before to 30 days after. Lines: plate boundaries and GEM active faults. Open on the live map
Nearby places
| Place | Distance | Est. shaking |
|---|---|---|
| No towns within 400 km. This is a remote area. | ||
Shaking is an estimate from the intensity prediction equation of Allen, Wald & Worden (2012), not an observation. Local ground and buildings can change it by a level or more. Likely felt out to about 138 km.
Every agency's solution
Agencies locate earthquakes with their own stations and methods, so their numbers differ. We match reports of the same event by time, distance and magnitude and show them side by side. The headline uses USGS, which has been reviewed by an analyst.
How big was it?
Felt by most people over a wide area. Can damage poorly built structures close to the epicentre.
It released roughly the energy of 674 t of TNT. Magnitude is logarithmic: each whole step means about 32 times more energy and 10 times larger waves on a seismogram. Depth matters too: at 35 km this was a shallow earthquake, which is felt more strongly at the surface than a deeper one of the same size.
M5.1 releases about 32× the energy of M4.1, and its waves are about 10× taller on a seismogram. Energy: 674 t of TNT vs 21 t of TNT.
Each square is the energy of one M4.1. Energy from log₁₀E = 1.5M + 4.8.
Aftershocks and nearby activity
1 later earthquake within 45 km; the largest was M4.9 16 h ago. Aftershock rates usually fall off roughly in proportion to 1/time.
Mainshock M5.1
1 later earthquake nearby. Aftershock rates typically fall off roughly as 1/time (Omori's law).
| Time after mainshock (hours) | Magnitude | Depth (km) |
|---|---|---|
| 0.96 | 4.9 | 35 |
Did you feel it?
Reports from people help show where shaking was strong. They are anonymous and shown here in aggregate.
Reports on SeismoAtlas
No reports yet.
Event id gfz2026szpf. First recorded here 28 Sept 2026, 17:32:06 UTC. Solutions: GFZ (geofon:gfz2026szpf); USGS (usgs:us6000ty2e). Cite as: SeismoAtlas, “M5.1 earthquake – South Sandwich Islands Region”, https://seismoatlas.com/earthquake/gfz2026szpf-m5-1-earthquake-south-sandwich-islands-region, data from USGS, GFZ.
JSON: /api/v1/events/gfz2026szpf. SeismoAtlas is not an official warning service.