Reviewed by USGS7y ago
M4.8 earthquake in South Sandwich Islands region
Sunday, December 30, 2018, 05:32:25 UTC · 56.643°S, 25.037°W
A magnitude 4.8 earthquake struck in South Sandwich Islands region on Sunday, December 30, 2018, 05:32:25 UTC, at a depth of 10.0 km (shallow). It is the strongest earthquake within 300 km since an M4.9 on December 27, 2018.
- Magnitude
- 4.8
- Light · mb
- Depth
- 10 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
239 tons of TNT
That is about 1/63 of the Hiroshima bomb. A magnitude 5.0 releases about 2 times more energy.
Tectonic setting
13 km
from the nearest mapped plate boundary, between the Sandwich and South American 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 PAGER estimate is available for this event.
After the main event
Aftershocks within 50 km
USGS lists 2 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M4.9 on December 30, 2018. 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 1,315 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.8South Sandwich Islands regionMay 26, 1964 · 165 km W of this epicenter
- 7.2South Sandwich Islands regionNovember 15, 1910 · 282 km S of this epicenter
- 7.2South Sandwich Islands regionDecember 27, 1991 · 69 km N of this epicenter
- 7.2South Sandwich Islands regionMay 28, 2016 · 125 km W of this epicenter
- 7.1South Sandwich Islands regionSeptember 8, 1961 · 146 km W of this epicenter
- 7.1South Sandwich Islands regionDecember 11, 2018 · 226 km S of this epicenter
- 7.0South Sandwich Islands regionJune 30, 2008 · 249 km SE of this epicenter
- 6.9South Sandwich Islands regionAugust 18, 1930 · 205 km NW 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 · 191 km away
- 1961M7.7
South Sandwich Islands
8 Sep 1961 · 144 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.