Location:

Period:

10 Sep 2024 21:18:56 - 10 Sep 2024 23:57:23 (2 hours 38 minutes)

Volcanoes in 100km radius:

Zavodovski(95km)

Earthquakes:

M 7.0+:

M 7.2; South Sandwich Islands region; (28 May 2016) (60km from the swarm center)

8 swarms found nearby.

2004

PS20040906.1(172.3km)

6 Sep

14 hours

7 earthquakes

2010

PS20101208.1(69.4km)

7 Dec

2 days 5 hours

10 earthquakes

2014

PS20140629.1(137.9km)

29 Jun

9 hours

11 earthquakes

PS20141211.1(119.3km)

11 Dec

9 hours

5 earthquakes

2017

PS20170511.1(89.6km)

10 May

1 day 5 hours

16 earthquakes

2018

PS20181116.1(104.2km)

15 Nov

12 hours

6 earthquakes

2021

PS20210812.3(177.4km)

12 Aug

1 day 9 hours

27 earthquakes

PS20210826.2(148.1km)

25 Aug

22 hours

6 earthquakes

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Seismic Swarm PS20240910.1 in the South Sandwich Islands Region

On 10 September 2024, a seismic swarm designated PS20240910.1 occurred in the South Sandwich Islands region. The sequence began at 21:18 UTC and concluded at 23:57 UTC, lasting 2 hours and 38 minutes. During this period, seven earthquakes were recorded, with magnitudes ranging from 4.6 to 5.7 and focal depths consistently at 10 km.

The events unfolded in rapid succession. The initial quake at 21:18:56 registered magnitude 5.0, followed by a 5.1 event at 21:39:12. Subsequent shocks included magnitudes of 5.0 at 21:48:45, 5.1 at 22:01:21, 4.6 at 22:12:09, a peak of 5.7 at 23:50:39, and a final 5.0 at 23:57:23. Such clustered activity without a dominant mainshock typifies swarm behavior, where multiple events of similar size occur over a short interval.

The South Sandwich Islands form part of a tectonically active arc in the South Atlantic Ocean. This region lies at the boundary between the South American and Scotia plates, where subduction drives ongoing deformation. The islands sit atop the small South Sandwich Plate, with the trench to the east marking the subduction interface. Volcanic activity and frequent seismicity result from this convergent margin setting. Depths around 10 km align with shallow crustal faulting common in the overriding plate or near the plate interface.

Historical records since 2000 indicate eight prior swarms in the area, occurring in 2004, 2010, 2014 (two instances), 2017, 2018, and 2021 (two instances). These episodes demonstrate recurrent swarm patterns in the region. A notable strong event was the magnitude 7.2 earthquake on 28 May 2016, located approximately 60 km from the 2024 swarm center, underscoring the potential for larger individual quakes amid background activity.

This latest swarm adds to the documented seismicity of the South Sandwich Islands, highlighting the persistent tectonic stresses in the subduction zone. Monitoring such sequences aids in understanding regional strain accumulation and release patterns.

References

USGS Earthquake Catalog (historical and regional data)
SeismoSight internal classification records for swarm parameters