Reviewed by USGS42y ago
M4.0 earthquake south of the Fiji Islands
Saturday, December 15, 1984, 19:06:47 UTC · 23.287°S, 179.604°W
A magnitude 4.0 earthquake struck south of the Fiji Islands on Saturday, December 15, 1984, 19:06:47 UTC, at a depth of 543.2 km (deep).
- Magnitude
- 4.0
- Light · mb
- Depth
- 543 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
15 tons of TNT
That is about 1/998 of the Hiroshima bomb. A magnitude 5.0 releases about 32 times more energy.
Tectonic setting
241 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
543 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 50 km
USGS has not published any M2.5+ earthquake within 50 km in the 30 days after this event.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 476 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.3Fiji regionMay 25, 1944 · 191 km N of this epicenter
- 7.3south of the Fiji IslandsMarch 30, 1972 · 289 km S of this epicenter
- 7.2Fiji regionOctober 9, 1967 · 238 km N of this epicenter
- 7.2south of the Fiji IslandsFebruary 10, 1969 · 170 km W of this epicenter
- 7.1Fiji regionFebruary 25, 1915 · 174 km N of this epicenter
- 7.1Fiji regionMay 4, 1924 · 245 km N of this epicenter
- 6.8Fiji regionJuly 20, 1939 · 245 km N of this epicenter
- 6.7south of the Fiji IslandsDecember 28, 1964 · 132 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:
- 1932M7.9
Kermadec Islands
26 May 1932 · 274 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.