Reviewed by USGS100y ago
M6.3 earthquake in South Indian Ocean
Saturday, April 16, 1927, 09:11:22 UTC · 34.218°S, 58.433°E
A magnitude 6.3 earthquake struck in South Indian Ocean on Saturday, April 16, 1927, 09:11:22 UTC, at a depth of 10.0 km (shallow). It is the strongest earthquake within 300 km since an M6.4 on March 21, 1927.
- Magnitude
- 6.3
- Strong · 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: 100 km aftershock search area
In context
How big was it, and why here?
Energy released
49 kilotons of TNT
That is about 3 times the Hiroshima bomb. It released about 102 times the energy of a magnitude 5.0.
Tectonic setting
146 km
from the nearest mapped plate boundary, between the Somali and Antarctic plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.
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 100 km
USGS lists 1 M2.5+ earthquake within 100 km in the following 30 days; the largest was M5.8 on May 10, 1927. 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 15 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.0South Indian OceanApril 11, 1925 · 47 km SE of this epicenter
- 7.0South Indian OceanSeptember 2, 1926 · 39 km SW of this epicenter
- 6.9South Indian OceanMay 3, 1925 · 60 km SW of this epicenter
- 6.6South Indian OceanMay 19, 1925 · 41 km W of this epicenter
- 6.4Southwest Indian RidgeMarch 21, 1927 · 97 km NW of this epicenter
- 6.3South Indian OceanOctober 12, 1925 · 20 km SW of this epicenter
- 6.3South Indian OceanMarch 15, 1926 · 146 km SW of this epicenter
- 6.3Southwest Indian RidgeMay 31, 1926 · 69 km NW of this epicenter