Reviewed by USGS60y ago
M6.4 earthquake in South Sandwich Islands region
Thursday, September 15, 1966, 11:51:59 UTC · 60.211°S, 27.022°W
A magnitude 6.4 earthquake struck in South Sandwich Islands region on Thursday, September 15, 1966, 11:51:59 UTC, at a depth of 38.4 km (shallow). It is the strongest earthquake within 300 km since an M6.8 on September 14, 1966.
- Magnitude
- 6.4
- Strong · mw
- Depth
- 38 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: 100 km aftershock search area
In context
How big was it, and why here?
Energy released
58 kilotons of TNT
That is about 4 times the Hiroshima bomb. It released about 122 times the energy of a magnitude 5.0.
Tectonic setting
17 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
38 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 100 km
USGS lists 4 M2.5+ earthquakes within 100 km in the following 30 days; the largest was M6.1 on October 11, 1966. 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 41 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.5South Sandwich Islands regionAugust 28, 1933 · 6 km SW of this epicenter
- 7.3South Sandwich Islands regionSeptember 1, 1961 · 105 km N of this epicenter
- 7.2South Sandwich Islands regionNovember 15, 1910 · 212 km NE of this epicenter
- 7.0South Sandwich Islands regionDecember 14, 1959 · 52 km NE of this epicenter
- 7.0South Sandwich Islands regionMarch 9, 1943 · 85 km W of this epicenter
- 7.0South Sandwich Islands regionMarch 21, 1926 · 193 km SE of this epicenter
- 6.8South Sandwich Islands regionSeptember 14, 1966 · 13 km W of this epicenter
- 6.7South Sandwich Islands regionJanuary 14, 1936 · 274 km E of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 2 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1961M7.7
South Sandwich Islands
5 Sep 1961 · 246 km away
- 1961M7.5
South Sandwich Islands
1 Sep 1961 · 81 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.