99 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, people at rest would likely notice it out to about 18 km (11 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 120 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.4 would have released about 32 times as much.

1. Mineral, Virginia 2011 M 5.8 130,000× the energy of this one
2. Magna, Utah 2020 M 5.7 89,000× the energy of this one
3. Around the size people start to feel M 3.0 7.9× the energy of this one
4. This earthquake M 2.4 about 120 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 2021-01-11 — about 11,000 times the energy of this one.

Before 2016, the USGS record lists 35 earthquakes of M5 or more within 50 km; the five largest:

1. 6.5 79 km SW of False Pass, Alaska · 30 km NNW of this epicentre Nov 19, 1993
2. 6.2 Unimak Island region, Alaska · 29 km S of this epicentre Oct 14, 1933
3. 6.2 102 km SSW of False Pass, Alaska · 4 km SSE of this epicentre Aug 20, 1939
4. 6.2 136 km S of False Pass, Alaska · 46 km SSE of this epicentre Apr 2, 1946
5. 6.2 115 km ESE of Akutan, Alaska · 22 km SSW of this epicentre Nov 20, 2005

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 54.0360, -164.0140. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.5 69 km SSW of False Pass, Alaska 15:07 UTC
2. 2.2 81 km SW of False Pass, Alaska 08:59 UTC
3. 2.8 95 km S of False Pass, Alaska 22:05 UTC
4. 2.6 89 km SSW of False Pass, Alaska 22:05 UTC
5. 2.3 107 km S of False Pass, Alaska 10:02 UTC
6. 2.6 139 km S of False Pass, Alaska 00:27 UTC
7. 2.3 122 km ESE of Akutan, Alaska 17:37 UTC
8. 1.9 86 km SW of False Pass, Alaska 15:22 UTC
9. 2.1 114 km ESE of Akutan, Alaska 09:36 UTC
10. 3.5 107 km SSW of False Pass, Alaska 21:46 UTC
11. 2.5 123 km SSW of False Pass, Alaska 18:03 UTC
12. 2.7 112 km SSW of False Pass, Alaska 17:44 UTC
13. 2.7 116 km ESE of Akutan, Alaska 16:56 UTC
14. 2.5 107 km S of False Pass, Alaska 07:04 UTC
15. 2.4 105 km E of Akutan, Alaska 18:09 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 23:15 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.