Reviewed by USGS10y ago
M5.9 earthquake in South Sandwich Islands region
Sunday, July 31, 2016, 11:33:20 UTC · 56.256°S, 27.537°W
A magnitude 5.9 earthquake struck in South Sandwich Islands region on Sunday, July 31, 2016, 11:33:20 UTC, at a depth of 99.0 km (intermediate). The USGS PAGER alert is green: low likelihood of casualties and damage. It is the strongest earthquake within 300 km since an M7.2 on May 28, 2016.
- Magnitude
- 5.9
- Moderate · mww
- Depth
- 99 km
- Intermediate
- Felt reports
- 0
- Max intensity I
- Est. shaking
- IV
- Light (ShakeMap)
- PAGER alert
- Green
- Impact estimate
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeDashed circle: 75 km aftershock search area
In context
How big was it, and why here?
Energy released
11 kilotons of TNT
That is about the energy of the Hiroshima bomb. It released about 22 times the energy of a magnitude 5.0.
Tectonic setting
114 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
99 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 populated area was estimated to feel noticeable shaking.
After the main event
Aftershocks within 75 km
USGS lists 10 M2.5+ earthquakes within 75 km in the following 30 days; the largest was M5.4 on August 27, 2016. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
- 4.7South Sandwich Islands region10y ago · 43 km SE of this epicenter
- 4.5South Sandwich Islands region10y ago · 49 km NE of this epicenter
- 5.4South Sandwich Islands region10y ago · 40 km E of this epicenter
- 4.5South Sandwich Islands region10y ago · 14 km NW of this epicenter
- 4.5South Sandwich Islands region10y ago · 69 km NE of this epicenter
- 4.6South Sandwich Islands region10y ago · 73 km NE of this epicenter
- 4.5South Sandwich Islands region10y ago · 45 km E of this epicenter
- 4.6South Sandwich Islands region10y ago · 71 km NE of this epicenter
Regional history
Past M5+ earthquakes within 300 km
USGS lists 1,096 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 · 150 km NW of this epicenter
- 7.8South Sandwich Islands regionMay 26, 1964 · 10 km SW of this epicenter
- 7.2South Sandwich Islands regionDecember 27, 1991 · 143 km E of this epicenter
- 7.2South Sandwich Islands regionMay 28, 2016 · 37 km E of this epicenter
- 7.1South Sandwich Islands regionSeptember 8, 1961 · 15 km SE of this epicenter
- 6.9South Sandwich Islands regionAugust 18, 1930 · 59 km NW of this epicenter
- 6.9South Sandwich Islands regionSeptember 13, 1921 · 99 km NW of this epicenter
- 6.9South Sandwich Islands regionSeptember 6, 2004 · 133 km NW 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 · 150 km away
- 1961M7.7
South Sandwich Islands
5 Sep 1961 · 197 km away
- 1961M7.7
South Sandwich Islands
8 Sep 1961 · 16 km away
- 2016M7.4
South Sandwich Islands
19 Aug 2016 · 292 km away · intensity III
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.