Reviewed by USGS36y ago
M5.7 earthquake in Carlsberg Ridge
Saturday, October 6, 1990, 09:08:09 UTC · 2.711°S, 67.908°E
A magnitude 5.7 earthquake struck in Carlsberg Ridge on Saturday, October 6, 1990, 09:08:09 UTC, at a depth of 10.0 km (shallow). It is the strongest earthquake within 300 km since an M5.8 on May 9, 1985.
- Magnitude
- 5.7
- Moderate · mw
- Depth
- 10 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: 75 km aftershock search area
In context
How big was it, and why here?
Energy released
5 kilotons of TNT
That is about 1/3 of the Hiroshima bomb. It released about 11 times the energy of a magnitude 5.0.
Tectonic setting
13 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
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
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 lists 1 M2.5+ earthquake within 75 km in the following 30 days; the largest was M4.9 on October 7, 1990. 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 44 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 6.2Carlsberg RidgeSeptember 8, 1922 · 89 km SW of this epicenter
- 6.0Chagos Archipelago regionFebruary 22, 1956 · 110 km S of this epicenter
- 6.0Carlsberg RidgeSeptember 7, 1955 · 51 km N of this epicenter
- 5.9Chagos Archipelago regionMarch 31, 1970 · 216 km SE of this epicenter
- 5.8Carlsberg RidgeMay 9, 1985 · 155 km N of this epicenter
- 5.8Carlsberg RidgeAugust 9, 1959 · 159 km N of this epicenter
- 5.7Chagos Archipelago regionJuly 10, 1935 · 187 km SE of this epicenter
- 5.7Chagos Archipelago regionApril 20, 1927 · 142 km S of this epicenter