60 km SSE of Halibut Cove, 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 44 km (27 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 1,900 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.2 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 180,000× the energy of this one
2. Mineral, Virginia 2011 M 5.8 7,900× the energy of this one
3. Magna, Utah 2020 M 5.7 5,600× the energy of this one
4. This earthquake M 3.2 about 1,900 lb of TNT
5. Around the size people start to feel M 3.0 this one released 2× 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 4.7 on 2022-12-12 — about 180 times the energy of this one.

Before 2016, the USGS record lists 5 earthquakes of M5 or more within 50 km:

1. 6.2 43 km ESE of Halibut Cove, Alaska · 29 km N of this epicentre Nov 3, 1945
2. 5.7 78 km SSE of Port Graham, Alaska · 49 km SSW of this epicentre Sep 6, 1964
3. 5.7 30 km ESE of Port Graham, Alaska · 41 km WNW of this epicentre May 5, 1999
4. 5.4 22 km ESE of Port Graham, Alaska · 49 km WNW of this epicentre Mar 28, 1964
5. 5.0 49 km SE of Port Graham, Alaska · 42 km WSW of this epicentre Apr 30, 2009

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 59.1380, -150.6400. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 1.9 32 km E of Halibut Cove, Alaska 12:44 UTC
2. 2.0 26 km SE of Halibut Cove, Alaska 08:36 UTC
3. 2.2 34 km ESE of Halibut Cove, Alaska 12:45 UTC
4. 2.2 50 km ESE of Halibut Cove, Alaska 00:12 UTC
5. 3.1 48 km ESE of Halibut Cove, Alaska 19:23 UTC
6. 3.8 49 km ESE of Halibut Cove, Alaska 19:14 UTC
7. 2.2 44 km SE of Fox River, Alaska 19:01 UTC
8. 2.0 42 km ESE of Halibut Cove, Alaska 09:30 UTC
9. 1.9 29 km SE of Halibut Cove, Alaska 13:18 UTC
10. 3.0 63 km SE of Port Graham, Alaska 15:13 UTC
11. 1.5 41 km SE of Fox River, Alaska 13:20 UTC
12. 2.0 28 km SSE of Halibut Cove, Alaska 23:01 UTC
13. 1.9 34 km ESE of Halibut Cove, Alaska 11:44 UTC
14. 1.7 82 km SE of Port Graham, Alaska 02:59 UTC
15. 1.9 67 km SE of Port Graham, Alaska 11:55 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 20:26 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.