Reviewed by USGS40y ago
M6.5 earthquake in Carlsberg Ridge
Monday, July 7, 1986, 16:26:56 UTC · 10.389°N, 56.832°E
A magnitude 6.5 earthquake struck in Carlsberg Ridge on Monday, July 7, 1986, 16:26:56 UTC, at a depth of 7.8 km (shallow). It is the strongest earthquake within 300 km since an M6.7 on April 8, 1983.
- Magnitude
- 6.5
- Strong · mw
- Depth
- 8 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
85 kilotons of TNT
That is about 6 times the Hiroshima bomb. It released about 178 times the energy of a magnitude 5.0.
Tectonic setting
29 km
from the nearest mapped plate boundary, between the Indian and Somali plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
8 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 2 M2.5+ earthquakes within 100 km in the following 30 days; the largest was M4.8 on July 17, 1986. 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 32 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.1Owen Fracture Zone regionMarch 31, 1954 · 237 km NE of this epicenter
- 7.0Carlsberg RidgeOctober 3, 1904 · 32 km NE of this epicenter
- 6.7Owen Fracture Zone regionApril 8, 1983 · 138 km NE of this epicenter
- 6.7170 km E of Hadibu, YemenDecember 18, 1908 · 270 km NW of this epicenter
- 6.2Owen Fracture Zone regionApril 20, 1980 · 178 km NE of this epicenter
- 6.2Carlsberg RidgeApril 11, 1954 · 49 km NE of this epicenter
- 6.2Carlsberg RidgeNovember 17, 1946 · 57 km NE of this epicenter
- 6.0Carlsberg RidgeFebruary 12, 1932 · 8 km W of this epicenter