Reviewed by USGS42y ago
M4.5 earthquake southeast of the Loyalty Islands
Tuesday, December 11, 1984, 11:59:41 UTC · 22.990°S, 171.796°E
A magnitude 4.5 earthquake struck southeast of the Loyalty Islands on Tuesday, December 11, 1984, 11:59:41 UTC, at a depth of 33.0 km (shallow). It is the strongest earthquake within 300 km since an M5.0 on December 10, 1984.
- Magnitude
- 4.5
- Light · mb
- Depth
- 33 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 earthquake
In context
How big was it, and why here?
Energy released
85 tons of TNT
That is about 1/178 of the Hiroshima bomb. A magnitude 5.0 releases about 6 times more energy.
Tectonic setting
18 km
from the nearest mapped plate boundary, between the New Hebrides and Australian plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.
Depth: shallow
33 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 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 322 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.6274 km ESE of Tadine, New CaledoniaMarch 16, 1928 · 160 km NW of this epicenter
- 7.2southeast of the Loyalty IslandsNovember 14, 1906 · 54 km N of this epicenter
- 7.2207 km E of Tadine, New CaledoniaOctober 25, 1980 · 234 km NW of this epicenter
- 7.1southeast of the Loyalty IslandsAugust 17, 1935 · 83 km NW of this epicenter
- 7.1southeast of the Loyalty IslandsApril 14, 1906 · 92 km NW of this epicenter
- 7.1175 km SE of Isangel, VanuatuMarch 30, 1910 · 289 km NW of this epicenter
- 7.1southeast of the Loyalty IslandsNovember 15, 1984 · 138 km NW of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 4 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1901M7.9
Loyalty Islands
9 Aug 1901 · 215 km away
Moderate damage ($1–5M)tsunami
- 1928M7.5
Loyalty Islands
16 Mar 1928 · 173 km away
- 1943M7.5
Loyalty Islands
14 Sep 1943 · 137 km away
- 1944M7.5
Loyalty Islands
5 Oct 1944 · 58 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.