QuakeScout
Magnitude4.4

Reviewed by USGS4y ago

M4.4 earthquake in South Sandwich Islands region

Saturday, August 20, 2022, 18:39:27 UTC · 57.130°S, 25.093°W

A magnitude 4.4 earthquake struck in South Sandwich Islands region on Saturday, August 20, 2022, 18:39:27 UTC, at a depth of 29.1 km (shallow).

Magnitude
4.4
Light · mb
Depth
29 km
Shallow
Felt reports
0
Did You Feel It?
Est. shaking
—
No ShakeMap
PAGER alert
None
Not issued
Tsunami
No flag
USGS feed

Outlined circle: this earthquakeDashed circle: 50 km aftershock search area

In context

How big was it, and why here?

Energy released

60 tons of TNT

That is about 1/251 of the Hiroshima bomb. A magnitude 5.0 releases about 8 times more energy.

Tectonic setting

43 km

from the nearest mapped plate boundary, between the Sandwich and South American plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.

Depth: shallow

29 km

Shallow earthquakes (under 70 km) produce the strongest surface shaking for their size, so they are the ones most likely to cause damage near the epicenter.

Did You Feel It?

Where it was felt

No “Did You Feel It?” reports have been published for this event yet. If you felt it, you can add your report on the USGS website.

I felt it — report to USGS ↗

USGS PAGER estimate

Who was exposed to shaking

USGS publishes PAGER impact estimates for significant earthquakes, usually within an hour. No PAGER estimate is available for this event.

After the main event

Aftershocks within 50 km

USGS lists 3 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M4.7 on September 6, 2022. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

M3M4M51h6h1d3d7d14d30dMainshock M4.4
Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.
  1. 4.7South Sandwich Islands region4y ago · 40 km NW of this epicenter
  2. 4.6South Sandwich Islands region4y ago · 23 km N of this epicenter
  3. 4.3South Sandwich Islands region4y ago · 4 km N of this epicenter

Regional history

Past M5+ earthquakes within 300 km

USGS lists 1,759 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

  1. 8.12021 South Sandwich Islands EarthquakeAugust 12, 2021 · 139 km S of this epicenter
  2. 7.8South Sandwich Islands regionMay 26, 1964 · 180 km NW of this epicenter
  3. 7.5South Sandwich Islands regionAugust 12, 2021 · 49 km S of this epicenter
  4. 7.3South Sandwich Islands regionSeptember 1, 1961 · 259 km S of this epicenter
  5. 7.2South Sandwich Islands regionNovember 15, 1910 · 230 km S of this epicenter
  6. 7.2South Sandwich Islands regionDecember 27, 1991 · 123 km N of this epicenter
  7. 7.2South Sandwich Islands regionMay 28, 2016 · 150 km NW of this epicenter
  8. 7.1South Sandwich Islands regionSeptember 8, 1961 · 164 km NW of this epicenter

History · NOAA

Deadliest earthquakes in this area

NOAA’s significant-earthquake database lists 5 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:

  1. 2021M8.1

    South Sandwich Islands

    12 Aug 2021 · 144 km away

    tsunami

  2. 1961M7.7

    South Sandwich Islands

    5 Sep 1961 · 149 km away

  3. 1961M7.7

    South Sandwich Islands

    8 Sep 1961 · 165 km away

  4. 1961M7.5

    South Sandwich Islands

    1 Sep 1961 · 293 km away

  5. 2021M7.5

    South Sandwich Islands

    12 Aug 2021 · 52 km away

NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.

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