Reviewed by USGSTonga23y ago
M4.0 earthquake 285 km WNW of Haveluloto, Tonga
Friday, April 18, 2003, 06:17:07 UTC · 19.851°S, 177.577°W
A magnitude 4.0 earthquake struck 285 km WNW of Haveluloto, Tonga on Friday, April 18, 2003, 06:17:07 UTC, at a depth of 500.0 km (deep).
- Magnitude
- 4.0
- Light · mb
- Depth
- 500 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
128 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
500 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 1,385 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.0TongaJanuary 4, 1903 · 270 km E of this epicenter
- 7.8159 km W of Pangai, TongaDecember 14, 1950 · 179 km E of this epicenter
- 7.8Fiji regionJanuary 1, 1919 · 79 km NW of this epicenter
- 7.8192 km WSW of Haveluloto, TongaOctober 14, 1997 · 264 km S of this epicenter
- 7.7Fiji regionAugust 19, 2002 · 287 km SW of this epicenter
- 7.6178 km E of Levuka, FijiFebruary 22, 1909 · 238 km NW of this epicenter
- 7.6240 km E of Levuka, FijiMarch 9, 1994 · 220 km NW of this epicenter
- 7.5262 km WNW of Haveluloto, TongaMay 21, 1962 · 29 km SE of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 11 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1937M8.1
Fiji Islands
16 Apr 1937 · 193 km away
- 1903M8.0
Tonga Islands
4 Jan 1903 · 270 km away
- 1909M7.8
Fiji Islands
22 Feb 1909 · 254 km away
- 1919M7.8
Fiji Islands
1 Jan 1919 · 79 km away
tsunami
- 1950M7.7
Tonga Islands
14 Dec 1950 · 170 km away · intensity VI
- 1997M7.7
Tonga Islands
14 Oct 1997 · 264 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.