113 km SW of Akhiok, Alaska

2021-02-04 01:12 UTC · 43 km deep · released about 43 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: 2021-02-04 01:12 UTC
Magnitude: M 2.1 (ml)
Depth: 43 km below the surface
Felt: no reports yet
Status: Reviewed by a seismologist

USGS · last changed by USGS 2050 days ago · we first saw it 2050 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 43 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.1 would have released about 32 times as much.

Mineral, Virginia 2011 M 5.8 350,000× the energy of this one
Magna, Utah 2020 M 5.7 250,000× the energy of this one
Around the size people start to feel M 3.0 22× the energy of this one
This earthquake M 2.1 about 43 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 56.3534, -155.6710. Map © OpenStreetMap contributors.

Aftershocks so far

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

1.6 143 km E of Chignik, Alaska 00:17 UTC
1.5 97 km WSW of Akhiok, Alaska 11:31 UTC
2.5 138 km WSW of Akhiok, Alaska 23:05 UTC
1.5 95 km WSW of Akhiok, Alaska 20:17 UTC
1.6 75 km WSW of Akhiok, Alaska 17:46 UTC
2.3 73 km WSW of Akhiok, Alaska 15:10 UTC
3.0 127 km WSW of Akhiok, Alaska 16:00 UTC
1.8 100 km WSW of Akhiok, Alaska 01:59 UTC
1.6 82 km SW of Akhiok, Alaska 13:35 UTC
2.2 122 km SW of Akhiok, Alaska 05:24 UTC
2.6 89 km WSW of Akhiok, Alaska 09:44 UTC
1.9 91 km WSW of Akhiok, Alaska 17:11 UTC
2.8 88 km WSW of Akhiok, Alaska 18:28 UTC
4.3 88 km WSW of Akhiok, Alaska 16:35 UTC
1.9 93 km WSW of Akhiok, Alaska 00:38 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 12:41 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.