Reviewed by USGS22y ago
M3.9 earthquake in Fiji region
Tuesday, September 21, 2004, 22:00:16 UTC · 17.714°S, 178.742°W
A magnitude 3.9 earthquake struck in Fiji region on Tuesday, September 21, 2004, 22:00:16 UTC, at a depth of 538.9 km (deep).
- Magnitude
- 3.9
- Minor · mb
- Depth
- 539 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 earthquakeDashed circle: 50 km aftershock search area
In context
How big was it, and why here?
Energy released
11 tons of TNT
That is about 1/1,410 of the Hiroshima bomb. A magnitude 5.0 releases about 45 times more energy.
Tectonic setting
202 km
from the nearest mapped plate boundary, between the Niuafo'ou and Australian plates. Earthquakes this far from a boundary happen on faults inside a plate, often less frequently but sometimes strongly.
Depth: deep
539 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 lists 15 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M5.5 on October 13, 2004. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
- 4.1195 km ENE of Levuka, Fiji22y ago · 46 km NW of this epicenter
- 3.9258 km ENE of Levuka, Fiji22y ago · 50 km E of this epicenter
- 4.4213 km E of Levuka, Fiji22y ago · 18 km S of this epicenter
- 4.8199 km E of Levuka, Fiji22y ago · 25 km S of this epicenter
- 3.9201 km ENE of Levuka, Fiji22y ago · 9 km W of this epicenter
- 4.4193 km ENE of Levuka, Fiji22y ago · 22 km NW of this epicenter
- 5.5193 km ENE of Levuka, Fiji22y ago · 23 km NW of this epicenter
- 4.2211 km E of Levuka, Fiji22y ago · 18 km S of this epicenter
Regional history
Past M5+ earthquakes within 300 km
USGS lists 915 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.8Fiji regionJanuary 1, 1919 · 192 km S of this epicenter
- 7.6178 km E of Levuka, FijiFebruary 22, 1909 · 60 km SW of this epicenter
- 7.6144 km SSW of Leava, Wallis and FutunaMay 23, 1956 · 254 km N of this epicenter
- 7.6240 km E of Levuka, FijiMarch 9, 1994 · 50 km SE of this epicenter
- 7.5262 km WNW of Haveluloto, TongaMay 21, 1962 · 296 km SE of this epicenter
- 7.4227 km E of Levuka, FijiAugust 21, 1910 · 23 km SE of this epicenter
- 7.2241 km WNW of Houma, TongaAugust 21, 1911 · 298 km SE of this epicenter
- 7.2Fiji regionMarch 31, 1907 · 194 km E of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 7 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1919M6.9
Rabi,Tunuloa Mission,Suvasavu
3 Oct 1919 · 198 km away · intensity VIII
Moderate damage ($1–5M)
- 1979M6.9
Fiji Islands
16 Nov 1979 · 169 km away
Moderate damage ($1–5M)tsunami
- 1932M6.4
Koro,Mudu,Suvasavu
8 Mar 1932 · 168 km away · intensity VII
Moderate damage ($1–5M)
- 1909M7.8
Fiji Islands
22 Feb 1909 · 42 km away
- 1919M7.8
Fiji Islands
1 Jan 1919 · 192 km away
tsunami
- 1994M7.6
Fiji Islands
9 Mar 1994 · 50 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.