Reviewed by USGS73y ago
M5.6 earthquake northern Mid-Atlantic Ridge
Tuesday, July 27, 1954, 20:57:53 UTC · 11.420°N, 43.688°W
A magnitude 5.6 earthquake struck northern Mid-Atlantic Ridge on Tuesday, July 27, 1954, 20:57:53 UTC, at a depth of 15.0 km (shallow). It is the strongest earthquake within 300 km since an M5.7 on July 26, 1954.
- Magnitude
- 5.6
- Moderate · mw
- Depth
- 15 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 earthquake
In context
How big was it, and why here?
Energy released
4 kilotons of TNT
That is about 1/4 of the Hiroshima bomb. It released about 8 times the energy of a magnitude 5.0.
Tectonic setting
23 km
from the nearest mapped plate boundary, between the African and South American plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
15 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 75 km
USGS has not published any M2.5+ earthquake within 75 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 7 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.1northern Mid-Atlantic RidgeOctober 13, 1925 · 173 km SE of this epicenter
- 7.1northern Mid-Atlantic RidgeDecember 2, 1918 · 9 km NE of this epicenter
- 7.0northern Mid-Atlantic RidgeFebruary 22, 1929 · 201 km SE of this epicenter
- 6.7northern Mid-Atlantic RidgeJuly 13, 1906 · 136 km SE of this epicenter
- 6.6northern Mid-Atlantic RidgeSeptember 3, 1927 · 69 km S of this epicenter
- 5.8northern Mid-Atlantic RidgeJune 22, 1936 · 275 km NW of this epicenter
- 5.7northern Mid-Atlantic RidgeJuly 26, 1954 · 20 km SE of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 1 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1925M7.5
North Atlantic Ridge
13 Oct 1925 · 190 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.