123 km SSW 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 89 km (55 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 11 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.9 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 16,000× the energy of this one
2. Mineral, Virginia 2011 M 5.8 710× the energy of this one
3. Magna, Utah 2020 M 5.7 500× the energy of this one
4. This earthquake M 3.9 about 11 tons of TNT
5. Around the size people start to feel M 3.0 this one released 22× 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 2024-12-09 — about 4,000 times the energy of this one.

Before 2016, the USGS record lists 62 earthquakes of M5 or more within 50 km; the five largest:

1. 6.8 90 km SSW of Adak, Alaska · 40 km NE of this epicentre Mar 11, 1957
2. 6.6 85 km SSW of Adak, Alaska · 44 km NE of this epicentre Jul 5, 1929
3. 6.4 76 km SSW of Adak, Alaska · 47 km NNE of this epicentre Jul 23, 1957
4. 6.2 101 km SW of Adak, Alaska · 45 km NNW of this epicentre Jun 2, 1940
5. 6.1 126 km SW of Adak, Alaska · 46 km NW of this epicentre Oct 1, 1992

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 50.8923, -177.4499. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.2 105 km SSW of Adak, Alaska 06:15 UTC
2. 3.6 133 km SSW of Adak, Alaska 06:13 UTC
3. 5.1 128 km SSW of Adak, Alaska 05:56 UTC
4. 3.0 122 km SSW of Adak, Alaska 05:51 UTC
5. 2.6 123 km SSW of Adak, Alaska 05:49 UTC
6. 2.2 109 km SW of Adak, Alaska 05:31 UTC
7. 3.5 127 km SSW of Adak, Alaska 05:23 UTC
8. 4.4 143 km SSW of Adak, Alaska 05:21 UTC
9. 4.0 122 km SSW of Adak, Alaska 05:20 UTC
10. 3.2 133 km SSW of Adak, Alaska 05:10 UTC
11. 3.4 114 km SSW of Adak, Alaska 05:09 UTC
12. 3.1 133 km SSW of Adak, Alaska 05:05 UTC
13. 2.2 116 km SSW of Adak, Alaska 04:50 UTC
14. 2.0 106 km SW of Adak, Alaska 04:47 UTC
15. 2.2 121 km SSW of Adak, Alaska 04:46 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 23:36 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.