Reviewed by USGS10y ago
M7.4 earthquake in South Georgia Island region
Friday, August 19, 2016, 07:32:22 UTC · 55.285°S, 31.877°W
A magnitude 7.4 earthquake struck in South Georgia Island region on Friday, August 19, 2016, 07:32:22 UTC, at a depth of 10.0 km (shallow). USGS received 1 “Did You Feel It?” report, with a maximum reported intensity of III (weak). The USGS PAGER alert is green: low likelihood of casualties and damage. It is the strongest earthquake within 300 km since an M7.8 on May 26, 1964.
- Magnitude
- 7.4
- Major · mww
- Depth
- 10 km
- Shallow
- Felt reports
- 1
- Max intensity III
- Est. shaking
- —
- No ShakeMap
- PAGER alert
- Green
- Impact estimate
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeDashed circle: 200 km aftershock search area
In context
How big was it, and why here?
Energy released
1.9 megatons of TNT
That is about 126 times the Hiroshima bomb. It released about 3,981 times the energy of a magnitude 5.0.
Tectonic setting
66 km
from the nearest mapped plate boundary, between the Scotia 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
Reports sent by people to USGS, grouped by place (most reports first). Intensity uses the Modified Mercalli scale (I–X): what people felt, not the magnitude.
| Place | Intensity | Reports | Distance |
|---|---|---|---|
| Grytviken, South Georgia, Falkland Islands | III · Weak | 1 | 320 km |
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 200 km
USGS lists 223 M2.5+ earthquakes within 200 km in the following 30 days; the largest was M6.1 on August 21, 2016. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
- 4.9South Georgia Island region10y ago · 39 km NE of this epicenter
- 5.2South Georgia Island region10y ago · 25 km E of this epicenter
- 4.9South Sandwich Islands region10y ago · 98 km NE of this epicenter
- 5.3South Sandwich Islands region10y ago · 89 km NE of this epicenter
- 4.7South Georgia Island region10y ago · 32 km E of this epicenter
- 4.5South Georgia Island region10y ago · 70 km NE of this epicenter
- 4.3South Sandwich Islands region10y ago · 78 km E of this epicenter
- 4.5South Georgia Island region10y ago · 73 km NE of this epicenter
Regional history
Past M5+ earthquakes within 300 km
USGS lists 416 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 · 160 km E of this epicenter
- 7.8South Sandwich Islands regionMay 26, 1964 · 288 km SE of this epicenter
- 6.9South Sandwich Islands regionAugust 18, 1930 · 251 km E of this epicenter
- 6.9South Sandwich Islands regionSeptember 13, 1921 · 206 km E of this epicenter
- 6.9South Sandwich Islands regionSeptember 6, 2004 · 184 km E of this epicenter
- 6.9South Sandwich Islands regionJune 29, 2014 · 223 km E of this epicenter
- 6.8South Sandwich Islands regionJanuary 30, 1963 · 210 km E of this epicenter
- 6.8South Sandwich Islands regionNovember 7, 2000 · 132 km E 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:
- 1929M8.1
South Sandwich Islands
27 Jun 1929 · 160 km away
- 2016M7.4
South Sandwich Islands
19 Aug 2016 · 0 km away · intensity III
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.