178 km SSW of Adak, Alaska

Yes. A magnitude 3.1 earthquake was recorded 178 km SSW of Adak, Alaska at 12:38 UTC on 2021-12-18, 10 km deep.

2021-12-18 12:38 UTC · 10 km deep · released about 1,300 lb 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: 2021-12-18 12:38 UTC
Magnitude: M 3.1 (ml)
Depth: 10 km below the surface
Felt: no reports yet
Nearest mapped fault: Alaska-Aleutian subduction zone, 6 km from its surface trace — near is not the same as on
Status: Reviewed by a seismologist

USGS · last changed by USGS 1718 days ago · we first saw it 1718 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

At this magnitude and depth, people at rest would likely notice it out to about 41 km (25 mi) from the epicentre. Estimated from magnitude, depth and distance with the intensity equation USGS Did You Feel It? uses; felt reports, where there are any, are the measurement.

How big was it?

This earthquake released about 1,300 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.1 would have released about 32 times as much.

Northridge, California 1994 M 6.7 250,000× the energy of this one
Mineral, Virginia 2011 M 5.8 11,000× the energy of this one
Magna, Utah 2020 M 5.7 7,900× the energy of this one
This earthquake M 3.1 about 1,300 lb of TNT
Around the size people start to feel M 3.0 this one released 1.4× 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.

For this area

The largest earthquake within 50 km since 2016 was M 5.4 on 2019-09-09 — about 2,800 times the energy of this one.

Before 2016, the USGS record lists 18 earthquakes of M5 or more within 50 km; the five largest:

6.5 184 km SSW of Adak, Alaska · 9 km WSW of this epicentre Aug 15, 2007
6.4 146 km S of Adak, Alaska · 49 km ENE of this epicentre Mar 10, 1957
6.1 198 km S of Adak, Alaska · 47 km SE of this epicentre May 22, 1957
6.1 189 km S of Adak, Alaska · 34 km ESE of this epicentre Jul 3, 1960
6.0 161 km SSW of Adak, Alaska · 23 km NNW of this epicentre Jan 11, 1934

Since 2016: the QuakeIndex catalogue (US, M1.5+), built from the USGS FDSN event service. Before 2016: USGS ComCat, M5+ from 1900. Distances are between epicentres. This is the record, not a forecast.

Where

Map loads when it scrolls into view

Aftershocks so far

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

4.0 130 km SSW of Adak, Alaska 00:55 UTC
2.5 132 km SSW of Adak, Alaska 00:51 UTC
3.6 133 km SSW of Adak, Alaska 00:43 UTC
5.5 132 km SSW of Adak, Alaska 00:39 UTC
3.4 129 km SSW of Adak, Alaska 20:42 UTC
2.6 220 km SSW of Adak, Alaska 16:46 UTC
3.5 167 km SSW of Adak, Alaska 13:16 UTC
3.2 181 km SSW of Adak, Alaska 17:17 UTC
2.3 220 km SSW of Adak, Alaska 22:28 UTC
3.0 174 km S of Adak, Alaska 08:14 UTC
2.2 188 km S of Adak, Alaska 13:30 UTC
2.2 183 km SSW of Adak, Alaska 13:17 UTC
3.0 202 km S of Adak, Alaska 12:25 UTC
2.8 172 km SSW of Adak, Alaska 13:18 UTC
2.9 189 km S of Adak, Alaska 00:36 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 20:16 UTC. QuakeIndex does not forecast aftershocks. When USGS issues an operational aftershock forecast it appears on the USGS event page.

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.