191 km S of Atka, Alaska

Yes. A magnitude 2.8 earthquake was recorded 191 km S of Atka, Alaska at 22:34 UTC on 2020-09-21, 10 km deep.

2020-09-21 22:34 UTC · 10 km deep · released about 480 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: 2020-09-21 22:34 UTC
Magnitude: M 2.8 (ml)
Depth: 10 km below the surface
Felt: no reports yet
Nearest mapped fault: Alaska-Aleutian subduction zone, 21 km from its surface trace — near is not the same as on
Status: Reviewed by a seismologist

USGS · last changed by USGS 2177 days ago · we first saw it 2177 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 25 km (16 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 480 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.8 would have released about 32 times as much.

Mineral, Virginia 2011 M 5.8 32,000× the energy of this one
Magna, Utah 2020 M 5.7 22,000× the energy of this one
Around the size people start to feel M 3.0 2× the energy of this one
This earthquake M 2.8 about 480 lb of TNT

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 4.1 on 2017-03-01 — about 89 times the energy of this one.

Before 2016, the USGS record lists 4 earthquakes of M5 or more within 50 km:

6.6 208 km S of Atka, Alaska · 20 km SSE of this epicentre Apr 30, 1913
6.1 193 km SE of Adak, Alaska · 33 km W of this epicentre Aug 19, 1992
5.6 178 km SE of Adak, Alaska · 42 km WNW of this epicentre Dec 26, 1971
5.6 185 km S of Atka, Alaska · 11 km NW of this epicentre May 25, 1988

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

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

2.7 Andreanof Islands, Aleutian Islands, Alaska 11:45 UTC
3.0 153 km S of Atka, Alaska 11:01 UTC
2.7 195 km S of Atka, Alaska 07:41 UTC
3.5 186 km SSW of Atka, Alaska 00:09 UTC
2.5 167 km SSW of Atka, Alaska 15:36 UTC
2.9 182 km S of Atka, Alaska 17:55 UTC
2.9 211 km SSW of Atka, Alaska 03:10 UTC
2.8 201 km SSW of Atka, Alaska 22:21 UTC
2.7 191 km SSW of Atka, Alaska 08:48 UTC
2.9 155 km S of Atka, Alaska 08:06 UTC
2.2 194 km S of Atka, Alaska 16:47 UTC
2.2 201 km SE of Adak, Alaska 02:25 UTC
2.3 146 km S of Atka, Alaska 06:08 UTC
2.7 209 km SSE of Adak, Alaska 14:15 UTC
2.3 187 km SE of Adak, Alaska 16:57 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 23:11 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.