M4.2 earthquake 179 km W of Neiafu, Tonga

Thursday, May 21, 2026, 18:24:55 UTC · 18.637°S, 175.681°W

A magnitude 4.2 earthquake struck 179 km W of Neiafu, Tonga on Thursday, May 21, 2026, 18:24:55 UTC, at a depth of 274.9 km (intermediate).

Magnitude: 4.2; Light · mb
Depth: 275 km; Intermediate
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

71 km

from the nearest mapped plate boundary, between the Tonga and Niuafo'ou plates. Earthquakes cluster along boundaries like this one, where plates collide, pull apart or slide past each other.

Depth: intermediate

275 km

Intermediate-depth earthquakes usually break inside a plate that is sinking into the mantle. Shaking spreads over a wide area but is gentler at the epicenter than a shallow quake of the same size.

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 3 M2.5+ earthquakes within 50 km in the following 30 days; the largest was M4.6 on May 25, 2026. Most nearby activity right after a large earthquake is aftershocks, which usually become less frequent over days and weeks.

Time after the mainshock on a logarithmic scale (first hours stretched), magnitude on the vertical axis. M2.5+ events from USGS.

Regional history

Past M5+ earthquakes within 300 km

USGS lists 2,060 M5.0+ earthquakes within 300 km before this one (catalog from 1900; older records are less complete). The strongest:

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. The most severe:

1865M8.0
Tonga Islands
18 Nov 1865 · 249 km away
Limited damage (under $1M)tsunami
2006M7.9
Tonga Islands
3 May 2006 · 238 km away · intensity VII
Limited damage (under $1M)tsunami
2018M8.2
Fiji Islands
19 Aug 2018 · 267 km away · intensity V
tsunami
1903M8.0
Tonga Islands
4 Jan 1903 · 168 km away
1902M7.8
Tonga Islands
9 Feb 1902 · 233 km away
1919M7.8
Fiji Islands
1 Jan 1919 · 263 km away
tsunami

NOAA NCEI Global Significant Earthquake Database. Historical figures are estimates; older records are incomplete.

Nearby trackers