Reviewed by USGS5y ago
M5.8 earthquake in Carlsberg Ridge
Friday, May 21, 2021, 16:02:36 UTC · 2.648°S, 68.103°E
A magnitude 5.8 earthquake struck in Carlsberg Ridge on Friday, May 21, 2021, 16:02:36 UTC, at a depth of 10.0 km (shallow). The USGS PAGER alert is green: low likelihood of casualties and damage. It is the strongest earthquake within 300 km since an M6.1 on August 31, 2020.
- Magnitude
- 5.8
- Moderate · mww
- Depth
- 10 km
- Shallow
- Felt reports
- 0
- Did You Feel It?
- Est. shaking
- —
- No ShakeMap
- PAGER alert
- Green
- Impact estimate
- Tsunami
- No flag
- USGS feed
Outlined circle: this earthquakeDashed circle: 75 km aftershock search areaColoured lines: estimated shaking intensity (USGS ShakeMap)
In context
How big was it, and why here?
Energy released
8 kilotons of TNT
That is about 1/2 of the Hiroshima bomb. It released about 16 times the energy of a magnitude 5.0.
Tectonic setting
3 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 populated area was estimated to feel noticeable shaking.
After the main event
Aftershocks within 75 km
USGS lists 2 M2.5+ earthquakes within 75 km in the following 30 days; the largest was M4.7 on May 21, 2021. 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 122 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.6Carlsberg RidgeJuly 15, 2003 · 31 km E of this epicenter
- 6.2Carlsberg RidgeSeptember 8, 1922 · 111 km SW of this epicenter
- 6.1Chagos Archipelago regionAugust 31, 2020 · 278 km SE of this epicenter
- 6.0Chagos Archipelago regionFebruary 22, 1956 · 112 km S of this epicenter
- 6.0Carlsberg RidgeSeptember 7, 1955 · 48 km NW of this epicenter
- 6.0Carlsberg RidgeJanuary 14, 1998 · 60 km N of this epicenter
- 5.9Chagos Archipelago regionMarch 31, 1970 · 200 km SE of this epicenter
- 5.8Carlsberg RidgeMay 9, 1985 · 153 km N 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:
- 2003M7.6
Felt In Maldives
15 Jul 2003 · 31 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.