How frequent are earthquakes in the area near the epicenter of this quake (within 100 km/61 mi)?

Q: How frequent are earthquakes in the area near the epicenter of this quake (within 100 km/61 mi)?

The area where this quake occurred has a very high level of seismic activity. Based on data from the past 14 years and our earthquake archive back to 1900, there are about 30.4 quakes on average per year in the area near the epicenter of this quake (within 100 km/61 mi). It has had at least 5 quakes above magnitude 7 since 1900, which suggests that larger earthquakes of this size occur infrequently, probably on average approximately every 20 to 25 years.

Very Strong Mag. 6.1 Earthquake - South Sandwich Islands Region on Friday, Aug 13, 2021, at 08:34 am (GMT -2) -

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Very strong mag. 6.1 earthquake - South Atlantic Ocean, South Georgia & South Sandwich Islands, on Friday, 13 Aug 2021 8:34 am (GMT -2)

A very strong magnitude 6.1 earthquake occurred in the South Atlantic Ocean 121 km (75 mi) from South Georgia and the South Sandwich Islands in the morning of Friday, Aug 13, 2021 at 8.34 am local time (GMT -2). The quake had a very shallow depth of 10 km (6 mi) and was not felt (or at least not reported so).

Very strong mag. 6.1 Earthquake - South Sandwich Islands Region on Friday, Aug 13, 2021, at 08:34 am (GMT -2)

Very strong magnitude 6.1 earthquake at 10 km depth

13 Aug 10:44 UTC: First to report: GFZ after 10 minutes.
13 Aug 10:44: Epicenter location corrected by 5 km (3.1 mi) towards NNW.
13 Aug 12:33: Magnitude recalculated from 5.5 to 6.1. Epicenter location corrected by 17 km (10.7 mi) towards WSW.

Earthquake details

Date & time	Aug 13, 2021 10:34:30 UTC
Local time at epicenter	Friday, Aug 13, 2021, at 08:34 am (GMT -2)
Status	Preliminary (automatic detection)
Magnitude	6.1
Depth	10 km
Epicenter latitude / longitude	60.56°S / 27.2°W South Atlantic Ocean, South Georgia & South Sandwich Islands
Seismic antipode	60.56°N / 152.8°E Russia
Shaking intensity	VI Strong shaking near epicenter
Felt	0 reports
Primary data source	GFZ (German Research Centre for Geosciences)
Nearest volcano	Thule Islands (117 km / 73 mi)
Weather at epicenter at time of quake	Overcast Clouds -17.3°C (1 F), humidity: 100%, wind: 3 m/s (6 kts) from NW
Estimated seismic energy released	8.9 x 10¹³ joules (24.8 gigawatt hours, equivalent to 21301 tons of TNT or 1.3 atomic bombs!) \| about seismic energy

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Most recent quakes Top 20 past 24 hrs Quakes in South Georgia and the South Sandwich Islands

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User-reports for this quake

There are no user reports for this quake yet.

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Compare Quake Data

Data for the same earthquake as reported by different agencies

The more agencies report about the same quake and post similar data, the more confidence you can have in the data. It takes normally up to a few hours until earthquake parameters are calculated with near-optimum precision.

Mag	Depth	Time GMT 2021-08-13	Epicenter	Agency
6.1	10 km 6.2 mi (*)	10:34:30	South Sandwich Islands Region	GFZ (German Research Centre for Geosciences)
6.3	10 km 6.2 mi (*)	10:34:28	SOUTH SANDWICH ISLANDS REGION 5.8 km (3.6 mi) epicenter difference with GFZ	EMSC (European-Mediterranean Seismological Centre)
5.3	10 km 6.2 mi (*)	10:34:33	Near Comodoro Rivadavia 21 km (13 mi) epicenter difference with GFZ	RENASS (Réseau National de Surveillance Sismique (RéNaSS))
6.3	10 km 6.2 mi (*)	10:34:29	South Sandwich Islands Region 7.8 km (4.8 mi) epicenter difference with GFZ	USGS (United States Geological Survey)
5.7	10 km 6.2 mi (*)	10:34:32	South Sandwich Islands Region 37 km (23 mi) epicenter difference with GFZ	BMKG (Meteorological, Climatological, and Geophysical Agency of Indonesia)
6.1	8.1 km 5 mi	10:34:29	South Sandwich Islands Region 10.7 km (6.6 mi) epicenter difference with GFZ	GeoAu (Geoscience Australia )

Notes:
(*) A depth given as 10 km often means that the the depth of the quake could not determined with sufficient accuracy.

Seismograms

Seismic station: Hope Point, South Georgia Island (HOPE/II network) | Distance from quake: 891 km / 553 mi | Show on map | Station Info

Seismic station Hope Point, South Georgia Island: vertical movement plot around time of quake (source: IRIS/BUD)

Seismogram (vertical component) around time of quake. Thin dotted red line indicates time of quake. Seismic waves arrive some time later, depending on distance. Bandpass filter applied: 0.02-5.0 Hz. Source: IRIS Buffer of Uniform Data (BUD) webtool

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Seismic station Hope Point, South Georgia Island: horizontal (E-W) movement plot around time of quake (source: IRIS/BUD)

Seismic station Hope Point, South Georgia Island: horizontal (N-S) movement plot around time of quake (source: IRIS/BUD)

Seismograms around time of quake, showing horizontal E-W and N-S ground movements. Source: IRIS Buffer of Uniform Data (BUD) webtool

Seismic station: Palmer Station, Antarctica (PMSA/IU network) | Distance from quake: 1909 km / 1186 mi | Show on map | Station Info

Seismic station Palmer Station, Antarctica: vertical movement plot around time of quake (source: IRIS/BUD)

Seismogram (vertical component) around time of quake. Thin dotted red line indicates time of quake. Seismic waves arrive some time later, depending on distance. Bandpass filter applied: 0.02-2.0 Hz. Source: IRIS Buffer of Uniform Data (BUD) webtool

Seismic station Palmer Station, Antarctica: horizontal (E-W) movement plot around time of quake (source: IRIS/BUD)

Seismic station Palmer Station, Antarctica: horizontal (N-S) movement plot around time of quake (source: IRIS/BUD)

Seismograms around time of quake.
Top: vertical movement, bottom: horizontal (E-W and N-S) movements. Source: IRIS Buffer of Uniform Data (BUD) webtool

Seismic station: Tristan da Cunha (TRIS/IU network) | Distance from quake: 2815 km / 1749 mi | Show on map | Station Info

Seismic station Tristan da Cunha: vertical movement plot around time of quake (source: IRIS/BUD)

Seismogram (vertical component) around time of quake. Thin dotted red line indicates time of quake. Seismic waves arrive some time later, depending on distance. Bandpass filter applied: 0.02-2.0 Hz. Source: IRIS Buffer of Uniform Data (BUD) webtool

Seismic station Tristan da Cunha: horizontal (E-W) movement plot around time of quake (source: IRIS/BUD)

Seismic station Tristan da Cunha: horizontal (N-S) movement plot around time of quake (source: IRIS/BUD)

Seismograms around time of quake.
Top: vertical movement, bottom: horizontal (E-W and N-S) movements. Source: IRIS Buffer of Uniform Data (BUD) webtool

Seismic station: Tornquist, Argentina (TRQA/IU network) | Distance from quake: 3477 km / 2161 mi | Show on map | Station Info

Seismic station Tornquist, Argentina: vertical movement plot around time of quake (source: IRIS/BUD)

Seismogram (vertical component) around time of quake. Thin dotted red line indicates time of quake. Seismic waves arrive some time later, depending on distance. Bandpass filter applied: 0.02-2.0 Hz. Source: IRIS Buffer of Uniform Data (BUD) webtool

Seismic station Tornquist, Argentina: horizontal (E-W) movement plot around time of quake (source: IRIS/BUD)

Seismic station Tornquist, Argentina: horizontal (N-S) movement plot around time of quake (source: IRIS/BUD)

Seismograms around time of quake.
Top: vertical movement, bottom: horizontal (E-W and N-S) movements. Source: IRIS Buffer of Uniform Data (BUD) webtool

Seismic station: Scott Base, Antarctica (SBA/IU network) | Distance from quake: 4595 km / 2855 mi | Show on map | Station Info

Seismic station Scott Base, Antarctica: vertical movement plot around time of quake (source: IRIS/BUD)

Seismogram (vertical component) around time of quake. Thin dotted red line indicates time of quake. Seismic waves arrive some time later, depending on distance. Bandpass filter applied: 0.02-2.0 Hz. Source: IRIS Buffer of Uniform Data (BUD) webtool

Seismic station Scott Base, Antarctica: horizontal (E-W) movement plot around time of quake (source: IRIS/BUD)

Seismic station Scott Base, Antarctica: horizontal (N-S) movement plot around time of quake (source: IRIS/BUD)

Seismograms around time of quake.
Top: vertical movement, bottom: horizontal (E-W and N-S) movements. Source: IRIS Buffer of Uniform Data (BUD) webtool

6 aftershocks for this quake

For this earthquake, 6 aftershocks have been detected so far. The strongest was a magnitude 5.2 quake that hit 3 days after the mainshock in 13.5 km (8 mi) distance, in South Sandwich Islands Region on Monday, Aug 16, 2021 on 05:17 pm (- local time GMT -2).
The most recent aftershock occurred 3 years ago South Sandwich Islands Region and had a magnitude of 5.0.

What are aftershocks?

Larger earthquakes (above magnitude 5 or so) such as this one are usually followed by smaller ones known as aftershocks that occur in the same area during the days, weeks, months or even years after the main shock.

[More info]

What about this quake?

Based on its magnitude, the fault that was active during the quake likely ruptured beneath a surface of approx. 126 km² (=49 sqare miles) as a first-order estimate. The length of the rupture zone thus was probably around 19 km (12 mi).

[More info]

Recorded aftershocks, latest first (6 quakes)

Date and Time GMT	Mag Depth	Distance	Region	Details
Oct 4, 2021 12:51 pm (GMT -2) 3 years ago 7 weeks after main shock	5.0 10 km	12 km (7.6 mi) N of main shock	South Sandwich Islands Region	More
Oct 4, 2021 01:54 am (GMT -2) 3 years ago 7 weeks after main shock	6.2 10 km	15 km (9.6 mi) W of main shock	South Sandwich Islands Region	More
Aug 27, 2021 11:47 am (GMT -2) 3 years ago 2 weeks after main shock	5.0 21 km	13 km (8.4 mi) E of main shock	South Sandwich Islands Region	More
Aug 16, 2021 05:17 pm (GMT -2) 3 years ago 3 days after main shock	5.2 10 km	14 km (8.4 mi) NE of main shock	South Sandwich Islands Region	More
Aug 16, 2021 04:44 am (GMT -2) 3 years ago 3 days after main shock	4.8 10 km	21 km (13 mi) SE of main shock	South Sandwich Islands Region	More
Aug 14, 2021 12:49 pm (GMT -2) 3 years ago 1 day 4 hours after main shock	5.1 39 km	16 km (9.8 mi) NE of main shock	South Sandwich Islands Region	More
Aug 13, 2021 08:34 am (GMT -2) 3 years ago	6.1 10 km	0 km - This quake	South Atlantic Ocean, South Georgia and the South Sandwich Islands Main Shock (this quake)	More

Map of aftershocks

Earthquake statistics

Average number of earthquakes

Based on data from the past 14 years and our earthquake archive back to 1900, there are about 30.4 quakes on average per year in the area near the epicenter of this quake (within 100 km/61 mi):

Mag. 7 or higher: 0.04 quakes per year (or 1 quake every 25 years)
Mag. 6 or higher: 0.26 quakes per year (or 1 quake every 3.8 years)
Mag. 5 or higher: 8.6 quakes per year
Mag. 4 or higher: 22.9 quakes per year
Mag. 3 or higher: 22.9 quakes per year
Mag. 2 or higher: 22.9 quakes per year

The area where this quake occurred has a very high level of seismic activity. It has had at least 5 quakes above magnitude 7 since 1900, which suggests that larger earthquakes of this size occur infrequently, probably on average approximately every 20 to 25 years.

Number of quakes per year

Previous quakes in the same area of this earthquake

Map to embed or share

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