120 km SSW of False Pass, Alaska

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

At this magnitude and depth, people at rest would likely notice it out to about 57 km (35 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 2.7 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.5 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 63,000× the energy of this one
2. Mineral, Virginia 2011 M 5.8 2,800× the energy of this one
3. Magna, Utah 2020 M 5.7 2,000× the energy of this one
4. This earthquake M 3.5 about 2.7 tons of TNT
5. Around the size people start to feel M 3.0 this one released 5.6× 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 2,000 times the energy of this one.

Before 2016, the USGS record lists 63 earthquakes of M5 or more within 50 km; the five largest:

1. 6.6 146 km ESE of Akutan, Alaska · 34 km SSE of this epicentre Apr 1, 1946
2. 6.6 92 km SE of Akutan, Alaska · 48 km WSW of this epicentre Feb 19, 2003
3. 6.5 83 km SE of Akutan, Alaska · 49 km WSW of this epicentre Oct 30, 1946
4. 6.5 81 km ESE of Akutan, Alaska · 45 km W of this epicentre Feb 6, 1974
5. 6.4 85 km ESE of Akutan, Alaska · 44 km W of this epicentre Nov 20, 1957

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 53.8244, -163.9851. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 3.5 121 km ESE of Akutan, Alaska 08:00 UTC
2. 2.8 121 km ESE of Akutan, Alaska 07:44 UTC
3. 2.3 121 km ESE of Akutan, Alaska 07:37 UTC
4. 5.1 Unimak Island region, Alaska 07:19 UTC
5. 1.8 94 km SSW of False Pass, Alaska 09:50 UTC
6. 2.1 113 km SSW of False Pass, Alaska 01:28 UTC
7. 1.9 104 km ESE of Akutan, Alaska 22:32 UTC
8. 1.8 92 km SSW of False Pass, Alaska 09:19 UTC
9. 4.0 150 km S of False Pass, Alaska 03:10 UTC
10. 1.9 91 km E of Akutan, Alaska 14:53 UTC
11. 2.2 92 km SSW of False Pass, Alaska 00:27 UTC
12. 2.2 108 km SSW of False Pass, Alaska 13:04 UTC
13. 3.0 116 km SSW of False Pass, Alaska 03:10 UTC
14. 2.6 103 km ESE of Akutan, Alaska 18:47 UTC
15. 3.8 116 km SSW of False Pass, Alaska 11:58 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 17:59 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.