Reviewed by USGS5y ago
M4.2 earthquake southeast of the Loyalty Islands
Sunday, April 25, 2021, 05:57:02 UTC · 23.612°S, 171.479°E
A magnitude 4.2 earthquake struck southeast of the Loyalty Islands on Sunday, April 25, 2021, 05:57:02 UTC, at a depth of 10.0 km (shallow).
- Magnitude
- 4.2
- Light · mb
- Depth
- 10 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
30 tons of TNT
That is about 1/500 of the Hiroshima bomb. A magnitude 5.0 releases about 16 times more energy.
Tectonic setting
55 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
10 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 2 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M5.2 on May 18, 2021. 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 1,003 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:
- 7.7southeast of the Loyalty IslandsFebruary 10, 2021 · 65 km N of this epicenter
- 7.7249 km E of Vao, New CaledoniaMay 16, 1995 · 175 km W of this epicenter
- 7.6274 km ESE of Tadine, New CaledoniaMarch 16, 1928 · 178 km NW of this epicenter
- 7.5southeast of the Loyalty IslandsJanuary 4, 1998 · 157 km N of this epicenter
- 7.5166 km ESE of Tadine, New CaledoniaDecember 5, 2018 · 280 km NW of this epicenter
- 7.3201 km ESE of Tadine, New CaledoniaDecember 27, 2003 · 250 km NW of this epicenter
- 7.2southeast of the Loyalty IslandsNovember 14, 1906 · 120 km N of this epicenter
History · NOAA
Deadliest earthquakes in this area
NOAA’s significant-earthquake database lists 13 damaging, deadly or tsunami-generating earthquakes within 300 km of this epicenter since 1700. The most severe:
- 1901M7.9
Loyalty Islands
9 Aug 1901 · 235 km away
Moderate damage ($1–5M)tsunami
- 2018M7.5
Loyalty Islands
5 Dec 2018 · 280 km away · intensity III
Limited damage (under $1M)tsunami
- 1995M7.7
Noumea; Vanuatu: Port-Vila
16 May 1995 · 175 km away · intensity III
tsunami
- 2021M7.7
Loyalty Islands
10 Feb 2021 · 63 km away · intensity VII
tsunami
- 1928M7.5
Loyalty Islands
16 Mar 1928 · 205 km away
- 1943M7.5
Loyalty Islands
14 Sep 1943 · 186 km away
NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.