131 km WNW of Adak, 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 2.7 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.5 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 63,000× the energy of this one
2. Mineral, Virginia 2011 M 5.8 2,800× the energy of this one
3. Magna, Utah 2020 M 5.7 2,000× the energy of this one
4. This earthquake M 3.5 about 2.7 tons of TNT
5. Around the size people start to feel M 3.0 this one released 5.6× 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 5.0 on 2016-11-08 — about 180 times the energy of this one.

Before 2016, the USGS record lists 14 earthquakes of M5 or more within 50 km; the five largest:

1. 6.4 170 km WNW of Adak, Alaska · 41 km NW of this epicentre Mar 13, 1992
2. 6.3 128 km W of Adak, Alaska · 30 km S of this epicentre May 10, 1939
3. 6.2 146 km WNW of Adak, Alaska · 20 km WSW of this epicentre Mar 22, 2008
4. 5.9 109 km WNW of Adak, Alaska · 25 km E of this epicentre Aug 5, 1940
5. 5.8 122 km W of Adak, Alaska · 48 km S of this epicentre Jul 2, 1939

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 52.2448, -178.4482. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.3 101 km W of Adak, Alaska 05:13 UTC
2. 1.5 150 km W of Adak, Alaska 02:44 UTC
3. 2.5 155 km WNW of Adak, Alaska 14:25 UTC
4. 2.9 133 km W of Adak, Alaska 00:13 UTC
5. 3.1 125 km W of Adak, Alaska 10:30 UTC
6. 3.6 129 km W of Adak, Alaska 03:45 UTC
7. 2.4 118 km WNW of Adak, Alaska 05:07 UTC
8. 1.9 129 km W of Adak, Alaska 13:09 UTC
9. 2.5 135 km W of Adak, Alaska 04:53 UTC
10. 2.1 155 km WNW of Adak, Alaska 04:37 UTC
11. 2.6 147 km W of Adak, Alaska 04:12 UTC
12. 3.8 134 km W of Adak, Alaska 06:34 UTC
13. 2.4 127 km WNW of Adak, Alaska 11:53 UTC
14. 2.2 110 km W of Adak, Alaska 13:42 UTC
15. 2.0 151 km W of Adak, Alaska 14:59 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 13:42 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.