106 km SE 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, people at rest would likely notice it out to about 75 km (47 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 7.6 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.8 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 22,000× the energy of this one
2. Mineral, Virginia 2011 M 5.8 1,000× the energy of this one
3. Magna, Utah 2020 M 5.7 710× the energy of this one
4. This earthquake M 3.8 about 7.6 tons of TNT
5. Around the size people start to feel M 3.0 this one released 16× 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 6.3 on 2019-11-24 — about 5,600 times the energy of this one.

Before 2016, the USGS record lists 134 earthquakes of M5 or more within 50 km; the five largest:

1. 8.6 1957 Atka, Alaska Earthquake · 27 km NNW of this epicentre Mar 9, 1957
2. 7.0 101 km SW of Atka, Alaska · 30 km NNE of this epicentre Aug 30, 2013
3. 6.9 100 km ESE of Adak, Alaska · 27 km NNE of this epicentre Oct 13, 1926
4. 6.8 99 km SW of Atka, Alaska · 31 km NE of this epicentre Mar 19, 1957
5. 6.8 100 km SW of Atka, Alaska · 30 km NNE of this epicentre Jun 13, 1957

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 51.2957, -175.4097. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.7 102 km ESE of Adak, Alaska 14:13 UTC
2. 2.4 114 km SSW of Atka, Alaska 08:41 UTC
3. 3.3 129 km SSW of Atka, Alaska 22:54 UTC
4. 2.1 65 km SE of Adak, Alaska 18:41 UTC
5. 3.2 87 km ESE of Adak, Alaska 02:42 UTC
6. 2.0 79 km ESE of Adak, Alaska 13:33 UTC
7. 2.2 96 km SW of Atka, Alaska 00:04 UTC
8. 3.8 93 km SW of Atka, Alaska 23:04 UTC
9. 4.6 94 km SW of Atka, Alaska 20:56 UTC
10. 2.0 84 km ESE of Adak, Alaska 01:50 UTC
11. 1.9 96 km SW of Atka, Alaska 18:05 UTC
12. 2.6 65 km SE of Adak, Alaska 17:04 UTC
13. 1.9 66 km SE of Adak, Alaska 11:58 UTC
14. 1.8 67 km SE of Adak, Alaska 20:37 UTC
15. 4.0 87 km SW of Atka, Alaska 18:23 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 07:32 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.