104 km SSW of False Pass, Alaska

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

At this magnitude and depth it was probably too small to be felt, even directly above it. 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 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.

1. Mineral, Virginia 2011 M 5.8 350,000× the energy of this one
2. Magna, Utah 2020 M 5.7 250,000× the energy of this one
3. Around the size people start to feel M 3.0 22× the energy of this one
4. 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.

For this area

The largest earthquake within 50 km since 2016 was M 5.1 on 2016-10-27 — about 32,000 times the energy of this one.

Before 2016, the USGS record lists 56 earthquakes of M5 or more within 50 km; the five largest:

1. 6.6 146 km ESE of Akutan, Alaska · 45 km S of this epicentre Apr 1, 1946
2. 6.5 79 km SW of False Pass, Alaska · 44 km NNW of this epicentre Nov 19, 1993
3. 6.2 Unimak Island region, Alaska · 20 km SSW of this epicentre Oct 14, 1933
4. 6.2 102 km SSW of False Pass, Alaska · 13 km WNW of this epicentre Aug 20, 1939
5. 6.2 136 km S of False Pass, Alaska · 34 km S of this epicentre Apr 2, 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

Epicentre 53.9474, -163.8254. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.1 108 km ESE of Akutan, Alaska 09:14 UTC
2. 2.1 92 km S of False Pass, Alaska 20:49 UTC
3. 3.0 91 km SSW of False Pass, Alaska 04:09 UTC
4. 1.9 87 km SSW of False Pass, Alaska 21:58 UTC
5. 2.1 92 km SSW of False Pass, Alaska 20:39 UTC
6. 2.1 108 km ESE of Akutan, Alaska 08:09 UTC
7. 1.9 115 km ESE of Akutan, Alaska 13:15 UTC
8. 2.9 109 km SSW of False Pass, Alaska 12:19 UTC
9. 2.6 Unimak Island region, Alaska 05:50 UTC
10. 2.2 103 km ESE of Akutan, Alaska 22:31 UTC
11. 2.1 136 km ESE of Akutan, Alaska 11:44 UTC
12. 2.7 107 km ESE of Akutan, Alaska 12:51 UTC
13. 2.0 Unimak Island region, Alaska 09:20 UTC
14. 1.8 92 km SSW of False Pass, Alaska 17:34 UTC
15. 1.9 112 km ESE of Akutan, Alaska 17:04 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 21:47 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.