192 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, people at rest would likely notice it out to about 11 km (7 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 950 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.0 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 350,000× the energy of this one
2. Mineral, Virginia 2011 M 5.8 16,000× the energy of this one
3. Magna, Utah 2020 M 5.7 11,000× the energy of this one
4. This earthquake M 3.0 about 950 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 6.0 on 2024-05-19 — about 32,000 times the energy of this one.

Before 2016, the USGS record lists 65 earthquakes of M5 or more within 50 km; the five largest:

1. 7.3 Fox Islands, Aleutian Islands, Alaska · 30 km WNW of this epicentre Jun 24, 2011
2. 6.9 170 km E of Atka, Alaska · 29 km NW of this epicentre Sep 2, 2011
3. 6.3 143 km E of Atka, Alaska · 50 km W of this epicentre Apr 5, 1957
4. 6.1 185 km ESE of Atka, Alaska · 18 km SW of this epicentre Dec 6, 1930
5. 6.1 207 km ESE of Atka, Alaska · 38 km S of this epicentre Mar 13, 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 51.9931, -171.4054. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 3.2 168 km E of Atka, Alaska 19:43 UTC
2. 2.8 172 km WSW of Nikolski, Alaska 21:32 UTC
3. 3.4 169 km WSW of Nikolski, Alaska 19:10 UTC
4. 3.4 158 km E of Atka, Alaska 01:23 UTC
5. 4.2 197 km SW of Nikolski, Alaska 05:37 UTC
6. 3.1 187 km E of Atka, Alaska 08:41 UTC
7. 3.0 192 km WSW of Nikolski, Alaska 07:02 UTC
8. 3.7 166 km ESE of Atka, Alaska 06:03 UTC
9. 3.3 193 km WSW of Nikolski, Alaska 20:16 UTC
10. 3.6 182 km WSW of Nikolski, Alaska 16:11 UTC
11. 3.5 194 km E of Atka, Alaska 02:23 UTC
12. 4.3 185 km E of Atka, Alaska 14:20 UTC
13. 3.9 186 km E of Atka, Alaska 12:05 UTC
14. 3.6 196 km WSW of Nikolski, Alaska 09:52 UTC
15. 4.7 189 km WSW of Nikolski, Alaska 09:36 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 05:50 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.