51 km N of Sutton-Alpine, 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 27 km (17 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 680 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.9 would have released about 32 times as much.

1. Mineral, Virginia 2011 M 5.8 22,000× the energy of this one
2. Magna, Utah 2020 M 5.7 16,000× the energy of this one
3. Around the size people start to feel M 3.0 1.4× the energy of this one
4. This earthquake M 2.9 about 680 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 4.6 on 2021-05-31 — about 350 times the energy of this one.

Before 2016, the USGS record lists 6 earthquakes of M5 or more within 50 km; the five largest:

1. 5.8 37 km ENE of Susitna North, Alaska · 21 km WNW of this epicentre Jul 3, 1929
2. 5.8 14 km NNE of Fishhook, Alaska · 45 km SSW of this epicentre Aug 14, 1984
3. 5.3 55 km NNE of Chickaloon, Alaska · 35 km E of this epicentre Jul 17, 1979
4. 5.1 25 km ENE of Susitna North, Alaska · 30 km W of this epicentre May 12, 1978
5. 5.0 59 km NW of Eureka Roadhouse, Alaska · 48 km ENE of this epicentre Feb 27, 1982

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 62.2370, -148.8170. Map © OpenStreetMap contributors.

Nearby places

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

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

1. 2.5 64 km ENE of Susitna North, Alaska 19:08 UTC
2. 1.4 18 km N of Chickaloon, Alaska 08:44 UTC
3. 1.1 15 km N of Chickaloon, Alaska 07:26 UTC
4. 1.6 20 km NNW of Chickaloon, Alaska 05:06 UTC
5. 1.7 65 km N of Chickaloon, Alaska 18:25 UTC
6. 2.3 54 km ENE of Susitna North, Alaska 02:41 UTC
7. 2.1 35 km N of Sutton-Alpine, Alaska 06:32 UTC
8. 2.7 35 km N of Sutton-Alpine, Alaska 03:10 UTC
9. 1.7 16 km N of Fishhook, Alaska 18:52 UTC
10. 1.4 39 km N of Sutton-Alpine, Alaska 07:16 UTC
11. 2.1 54 km N of Chickaloon, Alaska 10:05 UTC
12. 2.4 20 km N of Sutton-Alpine, Alaska 19:06 UTC
13. 2.3 62 km ENE of Susitna North, Alaska 07:06 UTC
14. 2.0 43 km ENE of Susitna North, Alaska 03:35 UTC
15. 2.2 39 km ENE of Susitna North, Alaska 22:43 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 23:55 UTC. QuakeIndex does not forecast aftershocks. When USGS issues an operational aftershock forecast it appears on the USGS event page.

Revisions

USGS refines a solution as more stations report. Every change we have seen is listed here.

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.