126 km S of Unalaska, 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 47 km (29 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 1.9 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.4 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 89,000× the energy of this one
2. Mineral, Virginia 2011 M 5.8 4,000× the energy of this one
3. Magna, Utah 2020 M 5.7 2,800× the energy of this one
4. This earthquake M 3.4 about 1.9 tons of TNT
5. Around the size people start to feel M 3.0 this one released 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 5.4 on 2016-07-26 — about 1,000 times the energy of this one.

Before 2016, the USGS record lists 44 earthquakes of M5 or more within 50 km; the five largest:

1. 6.5 127 km E of Nikolski, Alaska · 19 km W of this epicentre Oct 13, 2009
2. 6.4 118 km E of Nikolski, Alaska · 28 km W of this epicentre Mar 15, 1957
3. 6.4 123 km ESE of Nikolski, Alaska · 31 km WSW of this epicentre Oct 13, 2009
4. 6.3 136 km ESE of Nikolski, Alaska · 17 km SW of this epicentre Jan 12, 1952
5. 6.3 Fox Islands, Aleutian Islands, Alaska · 37 km WSW of this epicentre Jun 4, 1958

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 52.7408, -166.7199. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.3 150 km ESE of Nikolski, Alaska 07:48 UTC
2. 2.2 139 km ESE of Nikolski, Alaska 03:14 UTC
3. 2.5 141 km ESE of Nikolski, Alaska 03:04 UTC
4. 2.2 133 km ESE of Nikolski, Alaska 02:54 UTC
5. 3.3 144 km ESE of Nikolski, Alaska 00:34 UTC
6. 3.9 140 km S of Unalaska, Alaska 18:57 UTC
7. 2.5 127 km S of Unalaska, Alaska 13:58 UTC
8. 2.8 124 km ESE of Nikolski, Alaska 12:06 UTC
9. 2.1 121 km S of Unalaska, Alaska 11:10 UTC
10. 1.8 112 km S of Unalaska, Alaska 17:12 UTC
11. 2.1 139 km S of Unalaska, Alaska 07:37 UTC
12. 2.4 135 km ESE of Nikolski, Alaska 02:22 UTC
13. 2.2 143 km ESE of Nikolski, Alaska 01:39 UTC
14. 3.1 135 km ESE of Nikolski, Alaska 00:42 UTC
15. 4.6 120 km E of Nikolski, Alaska 00:40 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 06:00 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.