220 km WSW of Adak, Alaska

Yes. A magnitude 4.8 earthquake was recorded 220 km WSW of Adak, Alaska at 15:02 UTC on 2021-02-21, 10 km deep.

2021-02-21 15:02 UTC · 10 km deep · released about 240 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: 2021-02-21 15:02 UTC
Magnitude: M 4.8 (mb)
Depth: 10 km below the surface
Felt: no reports yet
Status: Reviewed by a seismologist

USGS · last changed by USGS 328 days ago · we first saw it 328 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon.

At this magnitude and depth, people at rest would likely notice it out to about 170 km (106 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 240 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.8 would have released about 32 times as much.

Northridge, California 1994 M 6.7 710× the energy of this one
Mineral, Virginia 2011 M 5.8 32× the energy of this one
Magna, Utah 2020 M 5.7 22× the energy of this one
This earthquake M 4.8 about 240 tons of TNT
Around the size people start to feel M 3.0 this one released 500× 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 5.8 on 2020-01-26 — about 32 times the energy of this one.

Before 2016, the USGS record lists 84 earthquakes of M5 or more within 50 km; the five largest:

6.7 254 km SW of Adak, Alaska · 42 km SSW of this epicentre Sep 14, 1905
6.7 192 km WSW of Adak, Alaska · 46 km N of this epicentre May 24, 1978
6.6 199 km WSW of Adak, Alaska · 43 km N of this epicentre Jul 8, 2006
6.5 184 km WSW of Adak, Alaska · 48 km NNE of this epicentre Dec 8, 1956
6.3 200 km SW of Adak, Alaska · 37 km ESE of this epicentre Oct 28, 1920

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

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

1.8 182 km WSW of Adak, Alaska 20:38 UTC
1.7 188 km WSW of Adak, Alaska 20:28 UTC
2.0 189 km WSW of Adak, Alaska 20:15 UTC
1.6 191 km WSW of Adak, Alaska 20:13 UTC
2.0 178 km WSW of Adak, Alaska 18:00 UTC
2.0 191 km WSW of Adak, Alaska 12:54 UTC
6.1 187 km WSW of Adak, Alaska 11:52 UTC
1.7 Andreanof Islands, Aleutian Islands, Alaska 07:14 UTC
3.4 184 km WSW of Adak, Alaska 07:13 UTC
3.2 187 km WSW of Adak, Alaska 07:08 UTC
5.5 185 km WSW of Adak, Alaska 07:02 UTC
1.5 208 km WSW of Adak, Alaska 00:47 UTC
2.7 221 km WSW of Adak, Alaska 23:02 UTC
2.5 219 km WSW of Adak, Alaska 21:43 UTC
2.8 220 km WSW of Adak, Alaska 12:56 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 17:46 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.