Reviewed by USGS53y ago
M6.6 earthquake in Southwest Indian Ridge
Wednesday, June 19, 1974, 02:55:19 UTC · 33.416°S, 56.875°E
A magnitude 6.6 earthquake struck in Southwest Indian Ridge on Wednesday, June 19, 1974, 02:55:19 UTC, at a depth of 33.0 km (shallow). It is the strongest earthquake within 300 km since an M7.5 on December 8, 1951.
- Magnitude
- 6.6
- 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 earthquake
In context
How big was it, and why here?
Energy released
120 kilotons of TNT
That is about 8 times the Hiroshima bomb. It released about 251 times the energy of a magnitude 5.0.
Tectonic setting
17 km
from the nearest mapped plate boundary, between the Somali and Antarctic 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 has not published any M2.5+ earthquake within 100 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 41 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.5South Indian OceanDecember 8, 1951 · 106 km SE of this epicenter
- 7.2South Indian OceanApril 7, 1916 · 263 km NW of this epicenter
- 7.1Southwest Indian RidgeJanuary 21, 1933 · 97 km SE of this epicenter
- 7.0South Indian OceanApril 11, 1925 · 213 km SE of this epicenter
- 7.0South Indian OceanSeptember 2, 1926 · 158 km SE of this epicenter
- 6.9South Indian OceanMay 3, 1925 · 158 km SE of this epicenter
- 6.6South Indian OceanMay 19, 1925 · 145 km SE of this epicenter
- 6.6Southwest Indian RidgeOctober 7, 1949 · 91 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:
- 1951M7.9
S
8 Dec 1951 · 66 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.