96 km S 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 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 170 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.5 would have released about 32 times as much.

1. Mineral, Virginia 2011 M 5.8 89,000× the energy of this one
2. Magna, Utah 2020 M 5.7 63,000× the energy of this one
3. Around the size people start to feel M 3.0 5.6× the energy of this one
4. This earthquake M 2.5 about 170 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 7,900 times the energy of this one.

Before 2016, the USGS record lists 49 earthquakes of M5 or more within 50 km; the five largest:

1. 6.5 79 km SW of False Pass, Alaska · 44 km NW of this epicentre Nov 19, 1993
2. 6.2 Unimak Island region, Alaska · 30 km SW of this epicentre Oct 14, 1933
3. 6.2 102 km SSW of False Pass, Alaska · 20 km W of this epicentre Aug 20, 1939
4. 6.2 136 km S of False Pass, Alaska · 40 km S of this epicentre Apr 2, 1946
5. 6.2 115 km ESE of Akutan, Alaska · 32 km SW 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 54.0038, -163.6924. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.9 61 km SSW of False Pass, Alaska 22:57 UTC
2. 2.0 62 km SSW of False Pass, Alaska 18:25 UTC
3. 2.3 112 km ESE of Akutan, Alaska 06:58 UTC
4. 1.9 86 km SSW of False Pass, Alaska 12:40 UTC
5. 2.5 Unimak Island region, Alaska 21:12 UTC
6. 2.9 129 km ESE of Akutan, Alaska 01:34 UTC
7. 2.1 110 km SSW of False Pass, Alaska 23:30 UTC
8. 2.6 106 km S of False Pass, Alaska 19:32 UTC
9. 2.2 65 km SSW of False Pass, Alaska 07:47 UTC
10. 2.2 120 km SSW of False Pass, Alaska 09:29 UTC
11. 2.2 92 km S of False Pass, Alaska 22:36 UTC
12. 2.0 97 km S of False Pass, Alaska 13:41 UTC
13. 3.1 129 km SSW of False Pass, Alaska 13:18 UTC
14. 3.0 111 km ESE of Akutan, Alaska 17:14 UTC
15. 1.9 123 km ESE of Akutan, Alaska 06:55 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 01:14 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.