128 km WSW of Adak, Alaska

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon.

At this magnitude and depth, people at rest would likely notice it out to about 124 km (77 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 60 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.4 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 2,800× the energy of this one
2. Mineral, Virginia 2011 M 5.8 130× the energy of this one
3. Magna, Utah 2020 M 5.7 89× the energy of this one
4. This earthquake M 4.4 about 60 tons of TNT
5. Around the size people start to feel M 3.0 this one released 130× 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 5.3 on 2016-07-03 — about 22 times the energy of this one.

Before 2016, the USGS record lists 227 earthquakes of M5 or more within 50 km; the five largest:

1. 7.3 88 km WSW of Adak, Alaska · 40 km ENE of this epicentre Jul 7, 1929
2. 7.2 162 km WSW of Adak, Alaska · 44 km WNW of this epicentre Mar 16, 1957
3. 7.0 114 km WSW of Adak, Alaska · 17 km NNE of this epicentre Jul 5, 1929
4. 7.0 148 km WSW of Adak, Alaska · 24 km W of this epicentre Mar 11, 1957
5. 6.9 151 km WSW of Adak, Alaska · 29 km WNW of this epicentre May 15, 1993

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 51.3158, -178.2573. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.1 125 km WSW of Adak, Alaska 00:08 UTC
2. 3.1 132 km WSW of Adak, Alaska 19:39 UTC
3. 2.9 133 km WSW of Adak, Alaska 15:40 UTC
4. 1.9 106 km WSW of Adak, Alaska 03:15 UTC
5. 2.1 119 km WSW of Adak, Alaska 19:56 UTC
6. 1.8 125 km W of Adak, Alaska 18:12 UTC
7. 1.9 126 km W of Adak, Alaska 06:09 UTC
8. 1.8 Andreanof Islands, Aleutian Islands, Alaska 04:18 UTC
9. 2.3 100 km SW of Adak, Alaska 23:24 UTC
10. 2.9 125 km WSW of Adak, Alaska 15:01 UTC
11. 2.9 130 km WSW of Adak, Alaska 12:38 UTC
12. 1.6 125 km W of Adak, Alaska 15:25 UTC
13. 3.0 127 km WSW of Adak, Alaska 09:39 UTC
14. 1.8 114 km WSW of Adak, Alaska 07:48 UTC
15. 1.7 124 km WSW of Adak, Alaska 05:17 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 05:54 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.