151 km SSE 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 41 km (25 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 1,300 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.1 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 250,000× the energy of this one
2. Mineral, Virginia 2011 M 5.8 11,000× the energy of this one
3. Magna, Utah 2020 M 5.7 7,900× the energy of this one
4. This earthquake M 3.1 about 1,300 lb of TNT
5. Around the size people start to feel M 3.0 this one released 1.4× 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 5.9 on 2016-10-27 — about 16,000 times the energy of this one.

Before 2016, the USGS record lists 26 earthquakes of M5 or more within 50 km; the five largest:

1. 8.6 The 1946 Unimak Island, Alaska Earthquake · 5 km S of this epicentre Apr 1, 1946
2. 6.2 172 km SSE of False Pass, Alaska · 22 km S of this epicentre Apr 2, 1946
3. 6.1 166 km S of False Pass, Alaska · 27 km SW of this epicentre Oct 14, 1929
4. 6.0 155 km S of False Pass, Alaska · 43 km WSW of this epicentre Apr 3, 1946
5. 6.0 129 km S of False Pass, Alaska · 43 km WNW of this epicentre Jan 14, 1961

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 53.5337, -162.8224. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 3.2 114 km S of False Pass, Alaska 09:35 UTC
2. 3.9 110 km S of False Pass, Alaska 09:29 UTC
3. 4.6 141 km S of False Pass, Alaska 22:41 UTC
4. 2.7 143 km S of False Pass, Alaska 21:27 UTC
5. 2.0 102 km SSE of False Pass, Alaska 22:31 UTC
6. 1.9 163 km S of False Pass, Alaska 22:22 UTC
7. 2.9 152 km S of False Pass, Alaska 12:42 UTC
8. 2.8 151 km S of False Pass, Alaska 13:02 UTC
9. 3.1 152 km S of False Pass, Alaska 13:31 UTC
10. 3.3 145 km S of False Pass, Alaska 10:43 UTC
11. 2.7 155 km S of False Pass, Alaska 10:01 UTC
12. 2.8 116 km S of False Pass, Alaska 07:35 UTC
13. 2.2 129 km SSE of False Pass, Alaska 04:04 UTC
14. 2.5 183 km S of False Pass, Alaska 02:33 UTC
15. 2.2 128 km S of False Pass, Alaska 12:01 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 04:02 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.