Earthquake near Elmendorf Air Force Base, AK

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 99 km (62 mi) from the epicentre. In Elmendorf Air Force Base, 19 km away, the estimate is intensity III (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: Eagle River 21 km, intensity III · Girdwood 27 km, intensity III · Anchorage 31 km, intensity III · Knik-Fairview 40 km, intensity III · Butte 44 km, intensity II · Palmer 49 km, intensity II. Estimated for each town centre; each link is that town's own record.

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 since 2016 was M 4.7 on 2018-12-09 — about 7.9 times the energy of this one.

Before 2016, the USGS record lists 13 earthquakes of M5 or more within 50 km; the five largest:

1. 6.0 21 km N of Whittier, Alaska · 41 km ESE of this epicentre Sep 14, 1932
2. 5.7 13 km S of Girdwood, Alaska · 40 km S of this epicentre Feb 19, 1928
3. 5.5 2 km ENE of Eagle River, Alaska · 20 km NNW of this epicentre May 11, 1965
4. 5.5 26 km SSW of Anchorage, Alaska · 47 km WSW of this epicentre May 24, 1995
5. 5.3 8 km NW of Knik-Fairview, Alaska · 48 km NNW of this epicentre May 6, 1997

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 61.1735, -149.3237. Map © OpenStreetMap contributors.

Nearby places

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

Aftershocks so far

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

1. 1.8 7 km SSE of Houston, Alaska 10:03 UTC
2. 2.6 18 km ESE of Elmendorf Air Force Base, Alaska 03:36 UTC
3. 2.3 7 km NNW of Knik, Alaska 16:54 UTC
4. 1.8 19 km NW of Girdwood, Alaska 11:12 UTC
5. 2.3 18 km N of Hope, Alaska 05:03 UTC
6. 1.6 5 km ESE of Big Lake, Alaska 08:01 UTC
7. 2.5 9 km WNW of Knik-Fairview, Alaska 19:34 UTC
8. 1.7 17 km S of Anchorage, Alaska 11:52 UTC
9. 1.6 15 km ESE of Elmendorf Air Force Base, Alaska 20:46 UTC
10. 1.6 17 km SSE of Anchorage, Alaska 00:39 UTC
11. 1.8 13 km ESE of Elmendorf Air Force Base, Alaska 13:58 UTC
12. 3.0 9 km ESE of Point MacKenzie, Alaska 00:55 UTC
13. 1.5 5 km E of Big Lake, Alaska 11:18 UTC
14. 1.8 2 km NW of Knik, Alaska 21:56 UTC
15. 1.8 26 km N of Girdwood, Alaska 23:26 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 20:17 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.