95 km SSW 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 328 km (204 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 (31 mi) since our catalogue begins in 2016. The previous largest was M 5.7 on 2017-05-08.

Before 2016, the USGS record lists 79 earthquakes of M5 or more within 50 km; the five largest:

1. 7.3 46 km SSW of Adak, Alaska · 49 km NNE of this epicentre Jun 10, 1996
2. 7.1 75 km S of Adak, Alaska · 24 km NE of this epicentre Mar 14, 1957
3. 7.0 101 km S of Adak, Alaska · 45 km E of this epicentre Sep 9, 1910
4. 7.0 69 km SW of Adak, Alaska · 45 km NNW of this epicentre May 2, 1971
5. 6.9 61 km SSW of Adak, Alaska · 34 km NNE of this epicentre Feb 7, 1971

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 51.0450, -176.9868. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 1.6 61 km SW of Adak, Alaska 12:36 UTC
2. 2.6 61 km S of Adak, Alaska 23:29 UTC
3. 3.7 89 km SW of Adak, Alaska 10:57 UTC
4. 2.8 104 km SSW of Adak, Alaska 10:09 UTC
5. 1.8 51 km S of Adak, Alaska 07:12 UTC
6. 1.9 60 km SSW of Adak, Alaska 01:42 UTC
7. 1.8 68 km S of Adak, Alaska 20:54 UTC
8. 3.5 98 km SSW of Adak, Alaska 13:14 UTC
9. 2.9 107 km SSW of Adak, Alaska 09:16 UTC
10. 2.3 101 km S of Adak, Alaska 17:34 UTC
11. 3.2 113 km SSW of Adak, Alaska 05:19 UTC
12. 3.0 108 km S of Adak, Alaska 05:06 UTC
13. 3.1 109 km SSW of Adak, Alaska 12:34 UTC
14. 2.3 100 km SSW of Adak, Alaska 00:24 UTC
15. 2.1 102 km SSW of Adak, Alaska 21:24 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 01:25 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.