Reviewed by USGS5y ago
M4.0 earthquake in South Sandwich Islands region
Thursday, October 7, 2021, 06:24:25 UTC · 60.219°S, 27.334°W
A magnitude 4.0 earthquake struck in South Sandwich Islands region on Thursday, October 7, 2021, 06:24:25 UTC, at a depth of 14.7 km (shallow).
- Magnitude
- 4.0
- Light · mb
- Depth
- 15 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 earthquake
In context
How big was it, and why here?
Energy released
15 tons of TNT
That is about 1/998 of the Hiroshima bomb. A magnitude 5.0 releases about 32 times more energy.
Tectonic setting
18 km
from the nearest mapped plate boundary, between the Australian and Antarctic plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
15 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 has not published any M2.5+ earthquake within 50 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 892 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 · 236 km NE of this epicenter
- 7.5South Sandwich Islands regionAugust 28, 1933 · 14 km E of this epicenter
- 7.3South Sandwich Islands regionSeptember 1, 1961 · 109 km N of this epicenter
- 7.3South Sandwich Islands regionJuly 15, 2013 · 143 km SE of this epicenter
- 7.2South Sandwich Islands regionNovember 15, 1910 · 227 km NE of this epicenter
- 7.2South Sandwich Islands regionOctober 22, 1983 · 115 km SE of this epicenter
- 7.1South Sandwich Islands regionAugust 22, 2021 · 136 km E of this epicenter
- 7.1South Sandwich Islands regionDecember 11, 2018 · 194 km N of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 3 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 2021M8.1
South Sandwich Islands
12 Aug 2021 · 231 km away
tsunami
- 1961M7.7
South Sandwich Islands
5 Sep 1961 · 247 km away
- 1961M7.5
South Sandwich Islands
1 Sep 1961 · 80 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.