26 km E of Skwentna, Alaska

2016-12-04 13:15 UTC · 8.9 km deep · released about 30 tons of TNT

Distance rings around the epicentre, with the nearest towns at their true direction and later quakes as coloured dots. Not a shaking map — see the USGS ShakeMap for that.

When: 2016-12-04 13:15 UTC
Magnitude: M 4.2 (mw)
Depth: 8.9 km below the surface
Felt: 145 reports · strongest reported intensity III
Measured shaking: intensity VI (ShakeMap)
USGS impact alert: green
Tsunami: USGS flagged this event for tsunami evaluation. Follow tsunami.gov for official messages.
Nearest: Matanuska-Susitna Borough, 80 km ENE
Status: Reviewed by a seismologist

USGS · last changed by USGS 1151 days ago · we first saw it 1151 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon. 145 people have reported feeling it to USGS.

How big was it?

This earthquake released about 30 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.2 would have released about 32 times as much.

Northridge, California 1994 M 6.7 5,600× the energy of this one
Mineral, Virginia 2011 M 5.8 250× the energy of this one
Magna, Utah 2020 M 5.7 180× the energy of this one
This earthquake M 4.2 about 30 tons of TNT
Around the size people start to feel M 3.0 this one released 63× more

Energy from the Gutenberg–Richter relation (log₁₀E = 1.5M + 4.8), rounded to two figures; bar length is magnitude, which is already a logarithm of energy. Magnitudes of past earthquakes from the USGS catalogue.

Where

Map loads when it scrolls into view

Epicentre 61.9700, -150.9023. Map © OpenStreetMap contributors.

Nearby places

Place	Distance	Direction
Matanuska-Susitna Borough, AK	80 km (50 mi)	WSW of here	earthquakes near Matanuska-Susitna Borough
Anchorage Municipality, AK	123 km (77 mi)	NW of here	earthquakes near Anchorage Municipality

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

58 earthquakes have been recorded within 50 km since this one.

1.6 21 km W of Willow, Alaska 16:03 UTC
1.5 30 km NE of Skwentna, Alaska 16:23 UTC
2.0 31 km NNW of Susitna, Alaska 02:23 UTC
2.2 29 km E of Skwentna, Alaska 07:07 UTC
1.7 27 km E of Skwentna, Alaska 02:32 UTC
2.1 29 km E of Skwentna, Alaska 00:58 UTC
1.5 29 km NNE of Skwentna, Alaska 20:19 UTC
2.0 11 km NE of Skwentna, Alaska 19:34 UTC
1.8 35 km SSW of Trapper Creek, Alaska 02:56 UTC
1.7 10 km SSE of Skwentna, Alaska 10:27 UTC
1.9 28 km WNW of Susitna, Alaska 07:32 UTC
2.4 21 km WSW of Petersville, Alaska 04:28 UTC
1.5 27 km E of Skwentna, Alaska 23:30 UTC
2.3 23 km ESE of Skwentna, Alaska 15:16 UTC
1.5 35 km S of Skwentna, Alaska 05:22 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 11:38 UTC. QuakeIndex does not forecast aftershocks. When USGS issues an operational aftershock forecast it appears on the USGS event page.

For this area

The largest earthquake within 50 km in our catalogue was M 4.5 on 2016-01-18 — it released about 2.8 times the energy of this one.

From the QuakeIndex catalogue, built from the USGS FDSN event service.

On USGS

The official USGS event page — the source of record for every value above
Did you feel it? Report it to USGS — reports go to USGS, not to us
ShakeMap for this event, when USGS has produced one

QuakeIndex does not issue warnings. For earthquake early warning see ShakeAlert.