87 km SSE of Adak, Alaska

This was a moderate earthquake. Shaking at this size can damage poorly built structures close to the epicentre.

At this magnitude and depth, people at rest would likely notice it out to about 327 km (203 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 11 kilotons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 6.9 would have released about 32 times as much.

1. Ridgecrest, California 2019 M 7.1 63× the energy of this one
2. Loma Prieta, California 1989 M 6.9 32× the energy of this one
3. Northridge, California 1994 M 6.7 16× the energy of this one
4. This earthquake M 5.9 about 11 kilotons of TNT
5. Mineral, Virginia 2011 M 5.8 this one released 1.4× more
6. Magna, Utah 2020 M 5.7 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 6.2 on 2025-03-21 — about 2.8 times the energy of this one.

Before 2016, the USGS record lists 95 earthquakes of M5 or more within 50 km; the five largest:

1. 7.1 75 km S of Adak, Alaska · 44 km W of this epicentre Mar 14, 1957
2. 7.0 101 km S of Adak, Alaska · 26 km SW of this epicentre Sep 9, 1910
3. 6.7 76 km SSE of Adak, Alaska · 12 km NNW of this epicentre Dec 10, 1905
4. 6.5 57 km S of Adak, Alaska · 44 km WNW of this epicentre Jun 18, 1986
5. 6.5 70 km SE of Adak, Alaska · 37 km NNE of this epicentre Sep 3, 2010

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 51.1563, -176.1097. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.6 50 km S of Adak, Alaska 09:23 UTC
2. 2.2 99 km SSE of Adak, Alaska 08:16 UTC
3. 3.3 83 km SSE of Adak, Alaska 06:19 UTC
4. 2.2 99 km SSE of Adak, Alaska 05:37 UTC
5. 3.3 107 km SSE of Adak, Alaska 05:33 UTC
6. 2.4 102 km SSE of Adak, Alaska 05:22 UTC
7. 2.8 101 km SSE of Adak, Alaska 04:30 UTC
8. 2.7 108 km SSE of Adak, Alaska 04:25 UTC
9. 2.2 75 km SSE of Adak, Alaska 04:21 UTC
10. 3.2 103 km SSE of Adak, Alaska 03:55 UTC
11. 3.6 100 km SSE of Adak, Alaska 03:47 UTC
12. 2.7 91 km SSE of Adak, Alaska 03:19 UTC
13. 3.6 96 km SSE of Adak, Alaska 03:10 UTC
14. 3.2 94 km SE of Adak, Alaska 03:00 UTC
15. 2.4 91 km SSE of Adak, Alaska 02:57 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 02:48 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.