154 km E of Atka, 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 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 4.6 on 2021-06-30 — about 180 times the energy of this one.

Before 2016, the USGS record lists 30 earthquakes of M5 or more within 50 km; the five largest:

1. 7.3 Fox Islands, Aleutian Islands, Alaska · 22 km SSE of this epicentre Jun 24, 2011
2. 6.9 170 km E of Atka, Alaska · 17 km ESE of this epicentre Sep 2, 2011
3. 6.3 143 km E of Atka, Alaska · 28 km SSW of this epicentre Apr 5, 1957
4. 6.1 185 km ESE of Atka, Alaska · 49 km SSE of this epicentre Dec 6, 1930
5. 6.1 157 km ESE of Atka, Alaska · 41 km S of this epicentre Jul 13, 1959

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 52.2349, -171.9412. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 3.3 172 km E of Atka, Alaska 07:24 UTC
2. 4.2 171 km E of Atka, Alaska 04:49 UTC
3. 3.9 139 km E of Atka, Alaska 03:00 UTC
4. 4.4 157 km ENE of Atka, Alaska 15:18 UTC
5. 2.9 173 km ESE of Atka, Alaska 18:23 UTC
6. 3.1 173 km E of Atka, Alaska 01:10 UTC
7. 3.0 139 km E of Atka, Alaska 07:22 UTC
8. 3.2 173 km E of Atka, Alaska 14:28 UTC
9. 2.1 135 km ESE of Atka, Alaska 18:32 UTC
10. 2.8 131 km ENE of Atka, Alaska 15:02 UTC
11. 2.4 163 km E of Atka, Alaska 09:50 UTC
12. 3.2 174 km ESE of Atka, Alaska 15:45 UTC
13. 3.0 132 km E of Atka, Alaska 06:18 UTC
14. 2.9 163 km E of Atka, Alaska 23:32 UTC
15. 3.7 174 km ESE of Atka, Alaska 23:12 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 06:02 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.