Reviewed by USGS49y ago
M4.4 earthquake east of the South Sandwich Islands
Saturday, August 27, 1977, 00:16:02 UTC · 59.528°S, 20.055°W
A magnitude 4.4 earthquake struck east of the South Sandwich Islands on Saturday, August 27, 1977, 00:16:02 UTC, at a depth of 33.0 km (shallow).
- Magnitude
- 4.4
- Light · mb
- Depth
- 33 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
80 km
from the nearest mapped plate boundary, between the Pacific and Australian plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
33 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 1 M2.5+ earthquake within 50 km in the following 30 days; the largest was M5.2 on September 5, 1977. 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 46 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.2South Sandwich Islands regionNovember 15, 1910 · 225 km W of this epicenter
- 7.1east of the South Sandwich IslandsAugust 26, 1977 · 28 km NW of this epicenter
- 7.0east of the South Sandwich IslandsOctober 6, 1973 · 166 km SW of this epicenter
- 7.0South Sandwich Islands regionMarch 21, 1926 · 261 km SW of this epicenter
- 6.7South Sandwich Islands regionAugust 22, 1967 · 276 km SW of this epicenter
- 6.7South Sandwich Islands regionJanuary 14, 1936 · 186 km SW of this epicenter
- 6.7east of the South Sandwich IslandsDecember 27, 1949 · 112 km SW of this epicenter
- 6.6east of the South Sandwich IslandsMarch 18, 1933 · 287 km E 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:
- 1973M7.5
Antarctica
6 Oct 1973 · 166 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.