Tonga earthquakes

M5.1 earthquake 63 km ENE of Kolonga, Tonga

A magnitude 5.1 earthquake struck 63 km ENE of Kolonga, Tonga on Thu, Apr 20, 2006, 4:30 AM GMT+13 (15:30 UTC), 10 km (6 mi) below the surface.

A larger quake followed: M8.0 2006 Tonga Earthquake. This one was a foreshock.

Nuku‘alofa forecast More in Tonga

Map

Where this earthquake was located, with the others nearby. Select one for its page.

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The earthquake

Magnitude: 5.1 (Mwc, centroid moment), moderate
Magnitude from: USGS National Earthquake Information Center
Local time: Thu, Apr 20, 2006, 4:30 AM GMT+13
UTC: 2006-04-19 15:30:05 UTC
Depth: 10.0 km (6.2 mi), shallow
Epicenter: 20.957° S, 174.486° W
Region: Tonga
Tsunami flag: No
Status: Reviewed by a seismologist

Magnitude estimates

Different scales measure different things and differ by a few tenths. The USGS marks one as preferred, and it is the one this page uses.

Mag.	Scale	Computed by	Notes
5.1	Mwc, centroid moment	USGS National Earthquake Information Center	Preferred · Reviewed
5.15	Mw, moment	ISC-GEM global catalog	Final · ±0.1
5.1	Mwc, centroid moment	Global CMT project	Preliminary

What happened

The USGS’s account of the effects of this earthquake.

no people dead or missing; no people injured; no buildings damaged or destroyed

From the USGS event page for usp000eexc. U.S. Geological Survey text and figures are in the public domain.

Did you feel it?

No one has reported feeling this quake to the USGS.

Fault motion and ground failure

How the rock slipped, from the moment tensor, and the USGS estimate of landslides and liquefaction.

Faulting: Reverse (thrust)
Nodal plane 1: Strike 198°, dip 30°, rake 84°
Nodal plane 2: Strike 25°, dip 60°, rake 94°

How well it is located

Reviewed by a seismologist.

Depth from: OPERATOR_ASSIGNED
Station coverage gap: 122°
Stations used: 100

Nearest places

Distance and direction from each place to the epicenter, with its forecast.

Nuku‘alofa, TongaPopulation 22,400. Forecast77 kmENE

Nearby

Within 100 km, magnitude 2.1 and up: 120 in the 60 days after this one and 1 in the 30 days before it.

After

The first 60 of 120.

Before

4.845 km SSE of Pangai, TongaFri, Mar 31, 1:19 AM GMT+13 · 7494 days ago · 35 km deep · 92 km away

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Sources

From the USGS Earthquake Hazards Program and its partner networks, event usp000eexc (also filed as gcmtc200604191530a, gcmt20060419153005, iscgem8320792). Read Mon, Oct 5, 2026, 3:01 AM UTC.