Unimak Island region, Alaska

Yes. A magnitude 4.0 earthquake was recorded in the Unimak Island region, Alaska at 23:37 UTC on 2022-10-13, 35 km deep.

2022-10-13 23:37 UTC · 35 km deep · released about 15 tons of TNT

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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: 2022-10-13 23:37 UTC
Magnitude: M 4.0 (mb)
Depth: 35 km below the surface
Felt: no reports yet
Measured shaking: intensity I (ShakeMap)
Status: Reviewed by a seismologist

USGS · last changed by USGS 1427 days ago · we first saw it 1427 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 90 km (56 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 15 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.0 would have released about 32 times as much.

Northridge, California 1994 M 6.7 11,000× the energy of this one
Mineral, Virginia 2011 M 5.8 500× the energy of this one
Magna, Utah 2020 M 5.7 350× the energy of this one
This earthquake M 4.0 about 15 tons of TNT
Around the size people start to feel M 3.0 this one released 32× 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 5.7 on 2020-08-13 — about 350 times the energy of this one.

Before 2016, the USGS record lists 64 earthquakes of M5 or more within 50 km; the five largest:

6.6 146 km ESE of Akutan, Alaska · 6 km NE of this epicentre Apr 1, 1946
6.2 Unimak Island region, Alaska · 32 km NNW of this epicentre Oct 14, 1933
6.2 136 km SE of Akutan, Alaska · 16 km WSW of this epicentre Apr 1, 1946
6.2 136 km S of False Pass, Alaska · 17 km NNE of this epicentre Apr 2, 1946
6.2 184 km SE of Akutan, Alaska · 42 km SE of this epicentre Apr 6, 1946

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

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Aftershocks so far

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

4.7 137 km SE of Akutan, Alaska 10:22 UTC
2.3 Unimak Island region, Alaska 02:29 UTC
1.9 105 km ESE of Akutan, Alaska 00:12 UTC
2.0 108 km SSW of False Pass, Alaska 23:02 UTC
1.9 104 km S of False Pass, Alaska 04:38 UTC
2.6 118 km SSW of False Pass, Alaska 13:47 UTC
2.7 155 km S of False Pass, Alaska 19:43 UTC
2.6 144 km SE of Akutan, Alaska 16:29 UTC
2.4 147 km ESE of Akutan, Alaska 12:30 UTC
2.8 140 km S of False Pass, Alaska 17:42 UTC
2.8 115 km SSW of False Pass, Alaska 22:54 UTC
2.2 Unimak Island region, Alaska 05:09 UTC
2.7 110 km SSW of False Pass, Alaska 21:48 UTC
2.6 120 km SSW of False Pass, Alaska 21:44 UTC
2.3 109 km S of False Pass, Alaska 16:25 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 02:58 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.