Reviewed by USGS5y ago
M5.2 earthquake in South Sandwich Islands region
Saturday, October 23, 2021, 00:34:17 UTC · 56.252°S, 27.901°W
A magnitude 5.2 earthquake struck in South Sandwich Islands region on Saturday, October 23, 2021, 00:34:17 UTC, at a depth of 112.3 km (intermediate). It is the strongest earthquake within 300 km since an M5.3 on October 7, 2021.
- Magnitude
- 5.2
- Moderate · mww
- Depth
- 112 km
- Intermediate
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- —
- No ShakeMap
- PAGER alert
- None
- Not issued
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquake
In context
How big was it, and why here?
Energy released
951 tons of TNT
That is about 1/16 of the Hiroshima bomb. It released about 2 times the energy of a magnitude 5.0.
Tectonic setting
126 km
from the nearest mapped plate boundary, between the Sandwich and South American plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.
Depth: intermediate
112 km
Intermediate-depth earthquakes usually break inside a plate that is sinking into the mantle. Shaking spreads over a wide area but is gentler at the epicenter than a shallow quake of the same size.
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 75 km
USGS has not published any M2.5+ earthquake within 75 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 1,370 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.12021 South Sandwich Islands EarthquakeAugust 12, 2021 · 284 km SE of this epicenter
- 8.11929 South Sandwich Islands EarthquakeJune 27, 1929 · 133 km NW of this epicenter
- 7.8South Sandwich Islands regionMay 26, 1964 · 17 km SE of this epicenter
- 7.5South Sandwich Islands regionAugust 12, 2021 · 227 km SE of this epicenter
- 7.4South Georgia Island regionAugust 19, 2016 · 271 km W of this epicenter
- 7.2South Sandwich Islands regionDecember 27, 1991 · 165 km E of this epicenter
- 7.2South Sandwich Islands regionMay 28, 2016 · 60 km E of this epicenter
- 7.1South Sandwich Islands regionSeptember 8, 1961 · 35 km E of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 6 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1929M8.1
South Sandwich Islands
27 Jun 1929 · 133 km away
- 2021M8.1
South Sandwich Islands
12 Aug 2021 · 286 km away
tsunami
- 1961M7.7
South Sandwich Islands
5 Sep 1961 · 202 km away
- 1961M7.7
South Sandwich Islands
8 Sep 1961 · 38 km away
- 2021M7.5
South Sandwich Islands
12 Aug 2021 · 222 km away
- 2016M7.4
South Sandwich Islands
19 Aug 2016 · 271 km away · intensity III
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.