Reviewed by USGS11y ago
M4.1 earthquake in South Sandwich Islands region
Saturday, April 4, 2015, 06:17:10 UTC · 57.319°S, 26.039°W
A magnitude 4.1 earthquake struck in South Sandwich Islands region on Saturday, April 4, 2015, 06:17:10 UTC, at a depth of 84.0 km (intermediate).
- Magnitude
- 4.1
- Light · mb
- Depth
- 84 km
- Intermediate
- Felt reports
- 0
- Max intensity I
- 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
21 tons of TNT
That is about 1/707 of the Hiroshima bomb. A magnitude 5.0 releases about 22 times more energy.
Tectonic setting
102 km
from the nearest mapped plate boundary, between the Sandwich and South American plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.
Depth: intermediate
84 km
Intermediate-depth earthquakes usually break inside a plate that is sinking into the mantle. Shaking spreads over a wide area but is gentler at the epicenter than a shallow quake of the same size.
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 M4.7 on April 21, 2015. 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 1,325 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.11929 South Sandwich Islands EarthquakeJune 27, 1929 · 297 km NW of this epicenter
- 7.8South Sandwich Islands regionMay 26, 1964 · 148 km NW of this epicenter
- 7.3South Sandwich Islands regionSeptember 1, 1961 · 222 km S of this epicenter
- 7.2South Sandwich Islands regionNovember 15, 1910 · 234 km SE of this epicenter
- 7.2South Sandwich Islands regionDecember 27, 1991 · 151 km N of this epicenter
- 7.1South Sandwich Islands regionSeptember 8, 1961 · 136 km NW of this epicenter
- 7.0South Sandwich Islands regionJune 30, 2008 · 254 km SE of this epicenter
- 7.0South Sandwich Islands regionDecember 14, 1959 · 291 km S of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 4 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 · 297 km away
- 1961M7.7
South Sandwich Islands
5 Sep 1961 · 95 km away
- 1961M7.7
South Sandwich Islands
8 Sep 1961 · 140 km away
- 1961M7.5
South Sandwich Islands
1 Sep 1961 · 253 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.