41 km S of Chiniak, Alaska

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon.

At this magnitude and depth, people at rest would likely notice it out to about 97 km (60 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 21 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.1 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 7,900× the energy of this one
2. Mineral, Virginia 2011 M 5.8 350× the energy of this one
3. Magna, Utah 2020 M 5.7 250× the energy of this one
4. This earthquake M 4.1 about 21 tons of TNT
5. Around the size people start to feel M 3.0 this one released 45× 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 (31 mi) since our catalogue begins in 2016. No other earthquake of M4 or more has been recorded this close in that time.

Before 2016, the USGS record lists 7 earthquakes of M5 or more within 50 km; the five largest:

1. 6.2 53 km ESE of Old Harbor, Alaska · 23 km SSW of this epicentre Mar 28, 1964
2. 5.9 25 km E of Old Harbor, Alaska · 33 km WSW of this epicentre Mar 28, 1964
3. 5.8 55 km SE of Chiniak, Alaska · 46 km E of this epicentre Mar 28, 1964
4. 5.6 39 km ESE of Chiniak, Alaska · 46 km ENE of this epicentre Mar 28, 1964
5. 5.6 45 km SSE of Chiniak, Alaska · 28 km E of this epicentre Apr 23, 1964

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 57.2393, -152.3602. Map © OpenStreetMap contributors.

Nearby places

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

Aftershocks so far

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

1. 2.2 19 km S of Womens Bay, Alaska 21:58 UTC
2. 1.9 35 km S of Chiniak, Alaska 12:07 UTC
3. 2.4 Kodiak Island region, Alaska 04:05 UTC
4. 2.1 7 km SSE of Womens Bay, Alaska 13:22 UTC
5. 2.0 7 km NW of Chiniak, Alaska 17:00 UTC
6. 1.6 48 km SE of Old Harbor, Alaska 03:33 UTC
7. 3.0 15 km S of Womens Bay, Alaska 11:53 UTC
8. 2.8 18 km ESE of Chiniak, Alaska 14:09 UTC
9. 2.5 8 km SE of Womens Bay, Alaska 16:36 UTC
10. 1.6 16 km ESE of Chiniak, Alaska 06:31 UTC
11. 1.7 18 km SSW of Womens Bay, Alaska 16:32 UTC
12. 2.1 18 km S of Womens Bay, Alaska 09:17 UTC
13. 1.9 18 km SW of Chiniak, Alaska 00:31 UTC
14. 1.5 Kodiak Island region, Alaska 08:09 UTC
15. 1.8 34 km E of Old Harbor, Alaska 02:58 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 21:32 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.