99 km SSE 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 14 km (9 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 85 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.3 would have released about 32 times as much.

1. Mineral, Virginia 2011 M 5.8 180,000× the energy of this one
2. Magna, Utah 2020 M 5.7 130,000× the energy of this one
3. Around the size people start to feel M 3.0 11× the energy of this one
4. This earthquake M 2.3 about 85 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 5.9 on 2016-10-27 — about 250,000 times the energy of this one.

Before 2016, the USGS record lists 38 earthquakes of M5 or more within 50 km; the five largest:

1. 6.5 88 km SE of False Pass, Alaska · 41 km NE of this epicentre Jun 21, 1987
2. 6.0 129 km S of False Pass, Alaska · 39 km SW of this epicentre Jan 14, 1961
3. 6.0 96 km SSW of False Pass, Alaska · 45 km W of this epicentre May 29, 1973
4. 6.0 137 km S of False Pass, Alaska · 42 km SSW of this epicentre May 22, 1988
5. 5.8 112 km SE of False Pass, Alaska · 46 km E of this epicentre Feb 24, 1939

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 53.9783, -163.0794. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 3.0 124 km SSE of False Pass, Alaska 17:48 UTC
2. 2.3 93 km S of False Pass, Alaska 00:28 UTC
3. 2.5 109 km S of False Pass, Alaska 12:40 UTC
4. 2.1 59 km SSE of False Pass, Alaska 21:38 UTC
5. 2.0 100 km SSE of False Pass, Alaska 19:44 UTC
6. 3.5 Unimak Island region, Alaska 13:28 UTC
7. 2.1 97 km S of False Pass, Alaska 22:03 UTC
8. 2.0 89 km S of False Pass, Alaska 16:30 UTC
9. 2.5 89 km SE of False Pass, Alaska 21:03 UTC
10. 2.2 74 km S of False Pass, Alaska 20:25 UTC
11. 2.5 106 km SSE of False Pass, Alaska 07:13 UTC
12. 2.6 109 km S of False Pass, Alaska 11:24 UTC
13. 2.5 93 km SE of False Pass, Alaska 09:06 UTC
14. 2.8 69 km S of False Pass, Alaska 00:59 UTC
15. 2.4 86 km SSE of False Pass, Alaska 22:34 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 23:47 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.