79 km W of Karluk, 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 46 km (29 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 5.3 on 2018-05-11 — about 1,400 times the energy of this one.

Before 2016, the USGS record lists 4 earthquakes of M5 or more within 50 km:

1. 5.4 60 km E of Ugashik, Alaska · 43 km WSW of this epicentre Sep 26, 1983
2. 5.2 55 km WSW of Karluk, Alaska · 39 km SE of this epicentre May 9, 1990
3. 5.2 67 km ESE of Egegik, Alaska · 46 km NW of this epicentre May 9, 1998
4. 5.0 54 km WNW of Karluk, Alaska · 28 km ENE of this epicentre Aug 29, 2001

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 57.6550, -155.7820. Map © OpenStreetMap contributors.

Nearby places

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

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

1. 1.4 64 km WNW of Karluk, Alaska 09:21 UTC
2. 1.5 88 km E of Ugashik, Alaska 14:55 UTC
3. 2.1 72 km WSW of Karluk, Alaska 13:24 UTC
4. 1.4 85 km WNW of Karluk, Alaska 08:40 UTC
5. 0.2 89 km WNW of Karluk, Alaska 20:54 UTC
6. 2.1 51 km WSW of Karluk, Alaska 13:50 UTC
7. 1.5 71 km WSW of Karluk, Alaska 06:03 UTC
8. 1.5 86 km W of Karluk, Alaska 10:52 UTC
9. 2.0 62 km WSW of Karluk, Alaska 05:09 UTC
10. 2.4 72 km WNW of Karluk, Alaska 09:06 UTC
11. 2.1 69 km E of Ugashik, Alaska 13:20 UTC
12. 0.9 90 km SE of King Salmon, Alaska 07:40 UTC
13. 1.7 84 km ESE of Egegik, Alaska 01:43 UTC
14. 0.7 89 km SE of King Salmon, Alaska 23:48 UTC
15. 0.9 89 km SSE of King Salmon, Alaska 21:48 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 02:32 UTC. QuakeIndex does not forecast aftershocks. When USGS issues an operational aftershock forecast it appears on the USGS event page.

Revisions

USGS refines a solution as more stations report. Every change we have seen is listed here.

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.