Reviewed by USGS88y ago
M6.8 earthquake in Fiji region
Thursday, July 20, 1939, 02:23:08 UTC · 21.128°S, 179.106°W
A magnitude 6.8 earthquake struck in Fiji region on Thursday, July 20, 1939, 02:23:08 UTC, at a depth of 635.0 km (deep). It is the strongest earthquake within 300 km since an M7.3 on April 16, 1937.
- Magnitude
- 6.8
- Strong · mw
- Depth
- 635 km
- Deep
- 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
239 kilotons of TNT
That is about 16 times the Hiroshima bomb. It released about 501 times the energy of a magnitude 5.0.
Tectonic setting
278 km
from the nearest mapped plate boundary, between the Tonga and Australian plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.
Depth: deep
635 km
Deep earthquakes (over 300 km) happen deep inside subducting plates. They rarely cause damage, but can be felt faintly over very large distances.
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 8 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.8Fiji regionJanuary 1, 1919 · 228 km NE of this epicenter
- 7.3227 km WNW of Haveluloto, TongaApril 16, 1937 · 195 km E of this epicenter
- 7.2241 km WNW of Houma, TongaAugust 21, 1911 · 229 km NE of this epicenter
- 7.2280 km WNW of Houma, TongaDecember 14, 1910 · 157 km NE of this epicenter
- 7.1Fiji regionFebruary 25, 1915 · 73 km S of this epicenter
- 7.1Fiji regionMay 4, 1924 · 40 km E of this epicenter
- 7.0254 km WNW of Houma, TongaApril 20, 1910 · 190 km NE of this epicenter
- 6.5209 km SSE of Suva, FijiJanuary 22, 1923 · 237 km NW of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 2 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1937M8.1
Fiji Islands
16 Apr 1937 · 222 km away
- 1919M7.8
Fiji Islands
1 Jan 1919 · 228 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.