Reviewed by USGS6y ago
M6.1 earthquake south of Africa
Saturday, September 26, 2020, 17:10:22 UTC · 48.025°S, 31.740°E
A magnitude 6.1 earthquake struck south of Africa on Saturday, September 26, 2020, 17:10:22 UTC, at a depth of 10.0 km (shallow). The USGS PAGER alert is green: low likelihood of casualties and damage. It is the strongest earthquake within 300 km since an M6.1 on November 17, 2014.
- Magnitude
- 6.1
- Strong · mww
- Depth
- 10 km
- Shallow
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- —
- No ShakeMap
- PAGER alert
- Green
- Impact estimate
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeDashed circle: 100 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)
In context
How big was it, and why here?
Energy released
21 kilotons of TNT
That is about the energy of the Hiroshima bomb. It released about 45 times the energy of a magnitude 5.0.
Tectonic setting
24 km
from the nearest mapped plate boundary, between the Antarctic and African plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
10 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 populated area was estimated to feel noticeable shaking.
After the main event
Aftershocks within 100 km
USGS lists 1 M2.5+ earthquake within 100 km in the following 30 days; the largest was M4.4 on October 5, 2020. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 51 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.01942 Southwest Indian Ridge EarthquakeNovember 10, 1942 · 227 km SW of this epicenter
- 6.3Prince Edward Islands regionMay 9, 2003 · 44 km SE of this epicenter
- 6.2south of AfricaJune 8, 1968 · 103 km S of this epicenter
- 6.2Prince Edward Islands regionAugust 21, 1978 · 72 km NE of this epicenter
- 6.2Prince Edward Islands regionAugust 7, 2005 · 175 km NE of this epicenter
- 6.1south of AfricaAugust 22, 1933 · 236 km SW of this epicenter
- 6.1south of AfricaFebruary 29, 1924 · 212 km S of this epicenter
- 6.1Prince Edward Islands regionNovember 17, 2014 · 243 km NE of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 1 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1942M7.9
Prince Edward Island
10 Nov 1942 · 165 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.