184 km SW of Nikolski, 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 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 6.0 on 2024-05-19 — about 45,000 times the energy of this one.

Before 2016, the USGS record lists 53 earthquakes of M5 or more within 50 km; the five largest:

1. 7.1 Fox Islands, Aleutian Islands, Alaska · 41 km SSW of this epicentre Dec 31, 1901
2. 6.2 179 km SW of Nikolski, Alaska · 8 km E of this epicentre Jun 4, 1956
3. 6.2 Fox Islands, Aleutian Islands, Alaska · 19 km SSE of this epicentre Mar 10, 1957
4. 6.1 207 km ESE of Atka, Alaska · 37 km WSW of this epicentre Mar 13, 1957
5. 6.1 Fox Islands, Aleutian Islands, Alaska · 3 km NW of this epicentre Jan 11, 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 51.7940, -170.8214. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.7 146 km SW of Nikolski, Alaska 02:15 UTC
2. 2.9 182 km SW of Nikolski, Alaska 03:03 UTC
3. 2.8 139 km SW of Nikolski, Alaska 03:40 UTC
4. 2.6 161 km SW of Nikolski, Alaska 17:08 UTC
5. 2.7 170 km SW of Nikolski, Alaska 13:57 UTC
6. 2.5 176 km SW of Nikolski, Alaska 04:41 UTC
7. 3.4 162 km SW of Nikolski, Alaska 17:44 UTC
8. 4.0 153 km SW of Nikolski, Alaska 16:21 UTC
9. 2.7 140 km SW of Nikolski, Alaska 22:47 UTC
10. 2.8 152 km SW of Nikolski, Alaska 07:58 UTC
11. 3.1 175 km SW of Nikolski, Alaska 17:10 UTC
12. 2.4 138 km SW of Nikolski, Alaska 15:04 UTC
13. 3.1 143 km SW of Nikolski, Alaska 23:28 UTC
14. 3.2 149 km SW of Nikolski, Alaska 07:02 UTC
15. 2.8 163 km SW of Nikolski, Alaska 18:15 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 05:58 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.