Reviewed by USGS98y ago
M8.1 earthquake 1929 South Sandwich Islands Earthquake
Thursday, June 27, 1929, 12:47:13 UTC · 55.373°S, 29.345°W
A magnitude 8.1 earthquake struck 1929 South Sandwich Islands Earthquake on Thursday, June 27, 1929, 12:47:13 UTC, at a depth of 15.0 km (shallow). No earthquake of this size or larger appears within 300 km in the USGS catalog since 1900.
- Magnitude
- 8.1
- Great · mw
- 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
21 megatons of TNT
That is about 1,415 times the Hiroshima bomb. It released about 44,668 times the energy of a magnitude 5.0.
Tectonic setting
29 km
from the nearest mapped plate boundary, between the Sandwich and Scotia 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 400 km
USGS has not published any M2.5+ earthquake within 400 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 7 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 6.9South Sandwich Islands regionSeptember 13, 1921 · 51 km SE of this epicenter
- 6.4South Sandwich Islands regionMay 1, 1923 · 284 km SE of this epicenter
- 6.4South Sandwich Islands regionJune 20, 1926 · 133 km SE of this epicenter
- 6.3South Sandwich Islands regionMarch 28, 1929 · 38 km NE of this epicenter
- 6.0South Sandwich Islands regionMay 15, 1928 · 92 km E of this epicenter
- 5.8South Sandwich Islands regionJuly 25, 1927 · 141 km S of this epicenter
- 5.8South Sandwich Islands regionAugust 16, 1927 · 217 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:
- 1929M8.1
South Sandwich Islands
27 Jun 1929 · 0 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.