Earthquake near Willow, AK

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 43 km (27 mi) from the epicentre. In Willow, 17 km away, the estimate is intensity II (weak). 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.

Likely felt in: Willow 17 km, intensity II · Susitna North 40 km, intensity II · Big Lake 41 km, intensity II. Estimated for each town centre; each link is that town's own record.

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 4.5 on 2016-01-18 — about 89 times the energy of this one.

Before 2016, the USGS record lists 19 earthquakes of M5 or more within 50 km; the five largest:

1. 6.9 27 km SE of Skwentna, Alaska · 40 km W of this epicentre Nov 3, 1943
2. 5.9 23 km NE of Willow, Alaska · 29 km ENE of this epicentre Jan 1, 1975
3. 5.7 19 km E of Skwentna, Alaska · 42 km WNW of this epicentre Nov 3, 1970
4. 5.6 11 km NW of Big Lake, Alaska · 32 km SSE of this epicentre Oct 7, 1966
5. 5.6 5 km N of Susitna, Alaska · 31 km SSW of this epicentre Dec 29, 1974

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 61.8559, -150.2735. 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. 1.5 30 km SSW of Trapper Creek, Alaska 21:01 UTC
2. 1.6 38 km SSW of Trapper Creek, Alaska 19:24 UTC
3. 1.5 8 km S of Big Lake, Alaska 22:40 UTC
4. 1.7 6 km ENE of Big Lake, Alaska 15:41 UTC
5. 1.6 7 km E of Big Lake, Alaska 10:40 UTC
6. 1.6 8 km S of Trapper Creek, Alaska 16:18 UTC
7. 1.9 8 km SSE of Trapper Creek, Alaska 16:16 UTC
8. 1.5 15 km NW of Susitna, Alaska 14:38 UTC
9. 1.5 7 km WSW of Houston, Alaska 09:13 UTC
10. 1.7 6 km W of Houston, Alaska 17:20 UTC
11. 1.7 18 km SSE of Susitna North, Alaska 07:20 UTC
12. 1.6 21 km W of Willow, Alaska 16:03 UTC
13. 1.5 2 km WNW of Houston, Alaska 06:06 UTC
14. 2.0 31 km NNW of Susitna, Alaska 02:23 UTC
15. 1.8 35 km SSW of Trapper Creek, Alaska 02:56 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 17:17 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.