Reviewed by USGS46y ago
M4.4 earthquake southeast of the Loyalty Islands
Wednesday, February 25, 1981, 15:21:09 UTC · 21.217°S, 169.437°E
A magnitude 4.4 earthquake struck southeast of the Loyalty Islands on Wednesday, February 25, 1981, 15:21:09 UTC, at a depth of 33.0 km (shallow).
- Magnitude
- 4.4
- 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 earthquakeDashed circle: 50 km aftershock search area
In context
How big was it, and why here?
Energy released
60 tons of TNT
That is about 1/251 of the Hiroshima bomb. A magnitude 5.0 releases about 8 times more energy.
Tectonic setting
51 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 lists 4 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M5.4 on February 26, 1981. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.
Regional history
Past M5+ earthquakes within 300 km
USGS lists 460 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 8.11920 Vanuatu EarthquakeSeptember 20, 1920 · 170 km NW of this epicenter
- 7.828 km ESE of Isangel, VanuatuJune 16, 1910 · 180 km N of this epicenter
- 7.663 km NW of Isangel, VanuatuOctober 14, 1913 · 244 km N of this epicenter
- 7.6274 km ESE of Tadine, New CaledoniaMarch 16, 1928 · 161 km SE of this epicenter
- 7.2southeast of the Loyalty IslandsNovember 14, 1906 · 268 km SE of this epicenter
- 7.247 km NNW of Isangel, VanuatuNovember 24, 1944 · 234 km N of this epicenter
- 7.262 km NE of Isangel, VanuatuJuly 2, 1953 · 237 km N of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 15 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700, which together caused about 26 recorded deaths. The most severe:
- 1875M8.1
Loyalty Islands: Lifou Island
28 Mar 1875 · 167 km away
26 deathsSevere damage ($5–24M)tsunami
- 1901M7.9
Loyalty Islands
9 Aug 1901 · 105 km away
Moderate damage ($1–5M)tsunami
- 1920M8.1
Loyalty Islands
20 Sep 1920 · 170 km away
Limited damage (under $1M)tsunami
- 1878M7.5
Tanna Island
10 Jan 1878 · 265 km away
Limited damage (under $1M)tsunami
- 1913M8.1
Vanuatu Islands
14 Oct 1913 · 196 km away
- 1878M8.0
Vanuatu Islands
11 Feb 1878 · 265 km away
tsunami
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.