174 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 118 km (73 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 43 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.3 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 4,000× the energy of this one
2. Mineral, Virginia 2011 M 5.8 180× the energy of this one
3. Magna, Utah 2020 M 5.7 130× the energy of this one
4. This earthquake M 4.3 about 43 tons of TNT
5. Around the size people start to feel M 3.0 this one released 89× 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 6.1 on 2021-09-24 — about 500 times the energy of this one.

Before 2016, the USGS record lists 210 earthquakes of M5 or more within 50 km; the five largest:

1. 7.2 162 km WSW of Adak, Alaska · 36 km N of this epicentre Mar 16, 1957
2. 7.0 148 km WSW of Adak, Alaska · 31 km NNE of this epicentre Mar 11, 1957
3. 6.9 151 km WSW of Adak, Alaska · 33 km NNE of this epicentre May 15, 1993
4. 6.8 177 km WSW of Adak, Alaska · 28 km NNW of this epicentre Oct 7, 1989
5. 6.7 194 km WSW of Adak, Alaska · 37 km WNW of this epicentre Sep 12, 1969

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 51.0944, -178.8203. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.0 163 km WSW of Adak, Alaska 01:45 UTC
2. 1.8 162 km WSW of Adak, Alaska 00:23 UTC
3. 2.0 163 km WSW of Adak, Alaska 00:00 UTC
4. 2.7 158 km WSW of Adak, Alaska 14:28 UTC
5. 1.8 165 km WSW of Adak, Alaska 10:29 UTC
6. 2.1 137 km WSW of Adak, Alaska 02:00 UTC
7. 1.8 186 km WSW of Adak, Alaska 16:00 UTC
8. 2.2 174 km WSW of Adak, Alaska 07:13 UTC
9. 1.9 195 km WSW of Adak, Alaska 15:32 UTC
10. 2.1 141 km WSW of Adak, Alaska 16:33 UTC
11. 2.1 133 km WSW of Adak, Alaska 13:52 UTC
12. 2.4 149 km WSW of Adak, Alaska 08:17 UTC
13. 2.1 152 km WSW of Adak, Alaska 09:21 UTC
14. 1.8 140 km WSW of Adak, Alaska 05:22 UTC
15. 1.9 136 km WSW of Adak, Alaska 11:52 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 12:46 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.