Reviewed by USGS13y ago
M4.6 earthquake in South Sandwich Islands region
Saturday, July 27, 2013, 04:28:47 UTC · 60.340°S, 26.830°W
A magnitude 4.6 earthquake struck in South Sandwich Islands region on Saturday, July 27, 2013, 04:28:47 UTC, at a depth of 25.2 km (shallow). It is the strongest earthquake within 300 km since an M4.7 on July 26, 2013.
- Magnitude
- 4.6
- Light · mb
- Depth
- 25 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
120 tons of TNT
That is about 1/126 of the Hiroshima bomb. A magnitude 5.0 releases about 4 times more energy.
Tectonic setting
17 km
from the nearest mapped plate boundary, between the Sandwich and Antarctic plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
25 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 M4.4 on August 12, 2013. 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 568 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 · 17 km NW of this epicenter
- 7.4east of the South Sandwich IslandsJanuary 2, 2006 · 293 km E of this epicenter
- 7.3South Sandwich Islands regionSeptember 1, 1961 · 119 km N of this epicenter
- 7.3South Sandwich Islands regionJuly 15, 2013 · 112 km SE of this epicenter
- 7.2South Sandwich Islands regionNovember 15, 1910 · 212 km NE of this epicenter
- 7.2South Sandwich Islands regionOctober 22, 1983 · 84 km SE of this epicenter
- 7.0east of the South Sandwich IslandsOctober 6, 1973 · 293 km E of this epicenter
- 7.0South Sandwich Islands regionJanuary 30, 1987 · 31 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:
- 1961M7.7
South Sandwich Islands
5 Sep 1961 · 260 km away
- 1961M7.5
South Sandwich Islands
1 Sep 1961 · 97 km away
- 1973M7.5
Antarctica
6 Oct 1973 · 293 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.