187 km SE of Adak, Alaska

2022-08-21 16:57 UTC · 22 km deep · released about 85 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: 2022-08-21 16:57 UTC
Magnitude: M 2.3 (ml)
Depth: 22 km below the surface
Felt: no reports yet
Status: Reviewed by a seismologist

USGS · last changed by USGS 1458 days ago · we first saw it 1458 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

How big was it?

This earthquake released about 85 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.3 would have released about 32 times as much.

Mineral, Virginia 2011 M 5.8 180,000× the energy of this one
Magna, Utah 2020 M 5.7 130,000× the energy of this one
Around the size people start to feel M 3.0 11× the energy of this one
This earthquake M 2.3 about 85 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.

Where

Map loads when it scrolls into view

Epicentre 50.5728, -174.9326. Map © OpenStreetMap contributors.

Aftershocks so far

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

2.6 216 km SSE of Adak, Alaska 23:46 UTC
3.1 199 km SSW of Atka, Alaska 19:10 UTC
3.3 176 km SE of Adak, Alaska 22:57 UTC
2.7 168 km SSW of Atka, Alaska 12:26 UTC
2.6 213 km SSE of Adak, Alaska 03:53 UTC
2.7 190 km S of Atka, Alaska 22:52 UTC
2.9 193 km S of Atka, Alaska 11:08 UTC
3.3 181 km SSE of Adak, Alaska 10:33 UTC
2.8 194 km S of Atka, Alaska 16:00 UTC
2.2 223 km S of Atka, Alaska 18:03 UTC
2.4 174 km SE of Adak, Alaska 00:45 UTC
3.0 205 km S of Atka, Alaska 11:50 UTC
3.1 192 km SE of Adak, Alaska 11:21 UTC
2.8 202 km SSW of Atka, Alaska 09:01 UTC
2.8 195 km SE of Adak, Alaska 00:50 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 00:27 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 4.3 on 2022-03-24 — it released about 1,000 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.