Reviewed by USGS28d ago
M5.1 earthquake in Southwest Indian Ridge
Saturday, August 29, 2026, 05:40:06 UTC · 31.826°S, 56.973°E
A magnitude 5.1 earthquake struck in Southwest Indian Ridge on Saturday, August 29, 2026, 05:40:06 UTC, at a depth of 10.0 km (shallow). It is the strongest earthquake within 300 km since an M5.3 on December 12, 2023.
- Magnitude
- 5.1
- Moderate · mb
- 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 earthquake
In context
How big was it, and why here?
Energy released
674 tons of TNT
That is about 1/22 of the Hiroshima bomb. It released about 1 times the energy of a magnitude 5.0.
Tectonic setting
16 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
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 has not published any M2.5+ earthquake within 75 km since this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 115 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 · 271 km S of this epicenter
- 7.2South Indian OceanApril 7, 1916 · 208 km W of this epicenter
- 7.1Southwest Indian RidgeJanuary 21, 1933 · 249 km S of this epicenter
- 6.6South Indian OceanMay 19, 1925 · 293 km S of this epicenter
- 6.6Southwest Indian RidgeJune 19, 1974 · 177 km S of this epicenter
- 6.6Southwest Indian RidgeOctober 7, 1949 · 237 km S of this epicenter
- 6.5South Indian OceanNovember 8, 1927 · 277 km SE of this epicenter
- 6.4Southwest Indian RidgeMarch 21, 1927 · 209 km S 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 · 242 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.