166 km SSW of Akhiok, 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 42 km (26 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 4.8 on 2021-07-29 — about 130 times the energy of this one.

Before 2016, the USGS record lists 8 earthquakes of M5 or more within 50 km; the five largest:

1. 6.9 143 km ESE of Chignik, Alaska · 39 km WNW of this epicentre Feb 13, 1951
2. 6.9 171 km SW of Akhiok, Alaska · 10 km W of this epicentre Feb 6, 1964
3. 6.2 148 km SSW of Akhiok, Alaska · 30 km E of this epicentre Nov 10, 1944
4. 5.9 124 km SSW of Akhiok, Alaska · 49 km ENE of this epicentre Nov 11, 1938
5. 5.9 169 km ESE of Chignik, Alaska · 22 km WSW of this epicentre Feb 6, 1964

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 55.7101, -155.6811. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.6 152 km ESE of Chignik, Alaska 18:57 UTC
2. 2.9 190 km SE of Chignik, Alaska 23:47 UTC
3. 3.9 174 km ESE of Chignik, Alaska 20:04 UTC
4. 2.3 162 km SSW of Akhiok, Alaska 14:09 UTC
5. 2.2 132 km SSW of Akhiok, Alaska 16:42 UTC
6. 2.5 148 km SW of Akhiok, Alaska 14:06 UTC
7. 2.4 187 km SSW of Akhiok, Alaska 14:15 UTC
8. 2.0 175 km SE of Chignik, Alaska 13:41 UTC
9. 3.6 148 km SW of Akhiok, Alaska 07:48 UTC
10. 3.1 185 km SSW of Akhiok, Alaska 05:18 UTC
11. 2.3 155 km ESE of Chignik, Alaska 01:05 UTC
12. 2.4 186 km SE of Chignik, Alaska 23:44 UTC
13. 2.3 186 km SSW of Akhiok, Alaska 23:24 UTC
14. 2.6 148 km ESE of Chignik, Alaska 11:37 UTC
15. 2.1 170 km SSW of Akhiok, Alaska 03:01 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 12:23 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.