Reviewed by USGS49y ago
M6.0 earthquake northern Mid-Atlantic Ridge
Tuesday, June 28, 1977, 19:18:35 UTC · 22.615°N, 45.111°W
A magnitude 6.0 earthquake struck northern Mid-Atlantic Ridge on Tuesday, June 28, 1977, 19:18:35 UTC, at a depth of 33.0 km (shallow). It is the strongest earthquake within 300 km since an M6.4 on May 19, 1963.
- Magnitude
- 6.0
- Strong · ms
- Depth
- 33 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: 100 km aftershock search area
In context
How big was it, and why here?
Energy released
15 kilotons of TNT
That is about the energy of the Hiroshima bomb. It released about 32 times the energy of a magnitude 5.0.
Tectonic setting
1 km
from the nearest mapped plate boundary, between the North American and African plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
33 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 100 km
USGS lists 1 M2.5+ earthquake within 100 km in the following 30 days; the largest was M4.9 on June 28, 1977. 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 20 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 6.8northern Mid-Atlantic RidgeJanuary 9, 1922 · 153 km NW of this epicenter
- 6.4northern Mid-Atlantic RidgeMay 19, 1963 · 143 km NW of this epicenter
- 6.2northern Mid-Atlantic RidgeOctober 14, 1924 · 178 km N of this epicenter
- 6.0northern Mid-Atlantic RidgeMay 6, 1944 · 10 km S of this epicenter
- 6.0northern Mid-Atlantic RidgeMay 23, 1935 · 72 km N of this epicenter
- 5.9northern Mid-Atlantic RidgeAugust 12, 1925 · 124 km NW of this epicenter
- 5.8northern Mid-Atlantic RidgeJune 3, 1962 · 50 km S of this epicenter
- 5.8northern Mid-Atlantic RidgeAugust 12, 1920 · 87 km W of this epicenter