141 km S of False Pass, 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 5.0 on 2016-06-18.

Before 2016, the USGS record lists 54 earthquakes of M5 or more within 50 km; the five largest:

1. 8.6 The 1946 Unimak Island, Alaska Earthquake · 30 km ESE of this epicentre Apr 1, 1946
2. 6.6 146 km ESE of Akutan, Alaska · 35 km W of this epicentre Apr 1, 1946
3. 6.2 136 km S of False Pass, Alaska · 34 km WNW of this epicentre Apr 2, 1946
4. 6.2 172 km SSE of False Pass, Alaska · 39 km SE of this epicentre Apr 2, 1946
5. 6.2 184 km SE of Akutan, Alaska · 46 km SSW of this epicentre Apr 6, 1946

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 53.5855, -163.2650. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.4 93 km S of False Pass, Alaska 03:09 UTC
2. 3.2 153 km S of False Pass, Alaska 18:01 UTC
3. 4.9 135 km S of False Pass, Alaska 08:36 UTC
4. 2.6 Unimak Island region, Alaska 05:08 UTC
5. 3.4 131 km S of False Pass, Alaska 01:53 UTC
6. 2.5 126 km S of False Pass, Alaska 00:17 UTC
7. 3.3 150 km S of False Pass, Alaska 23:59 UTC
8. 2.5 150 km S of False Pass, Alaska 23:52 UTC
9. 2.4 149 km S of False Pass, Alaska 23:20 UTC
10. 2.5 156 km S of False Pass, Alaska 23:11 UTC
11. 2.5 157 km S of False Pass, Alaska 23:09 UTC
12. 3.3 159 km S of False Pass, Alaska 22:59 UTC
13. 2.6 155 km S of False Pass, Alaska 22:54 UTC
14. 4.2 139 km S of False Pass, Alaska 22:46 UTC
15. 2.5 152 km S of False Pass, Alaska 21:34 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 17:50 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.