123 km WSW of Adak, Alaska

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

At this magnitude and depth, people at rest would likely notice it out to about 5 km (3 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 30 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.0 would have released about 32 times as much.

1. Mineral, Virginia 2011 M 5.8 500,000× the energy of this one
2. Magna, Utah 2020 M 5.7 350,000× the energy of this one
3. Around the size people start to feel M 3.0 32× the energy of this one
4. This earthquake M 2.0 about 30 lb of TNT

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 6.5 on 2018-08-15 — about 5,600,000 times the energy of this one.

Before 2016, the USGS record lists 228 earthquakes of M5 or more within 50 km; the five largest:

1. 7.9 77 km WSW of Adak, Alaska · 47 km ENE of this epicentre Jun 10, 1996
2. 7.3 88 km WSW of Adak, Alaska · 37 km E of this epicentre Jul 7, 1929
3. 7.2 162 km WSW of Adak, Alaska · 42 km W of this epicentre Mar 16, 1957
4. 7.0 114 km WSW of Adak, Alaska · 9 km ENE of this epicentre Jul 5, 1929
5. 7.0 148 km WSW of Adak, Alaska · 25 km WSW of this epicentre Mar 11, 1957

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 51.4164, -178.2672. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.1 155 km WSW of Adak, Alaska 23:54 UTC
2. 2.9 163 km SW of Adak, Alaska 08:22 UTC
3. 3.1 147 km WSW of Adak, Alaska 04:25 UTC
4. 1.7 142 km WSW of Adak, Alaska 13:44 UTC
5. 3.4 Andreanof Islands, Aleutian Islands, Alaska 10:16 UTC
6. 1.5 100 km WSW of Adak, Alaska 09:37 UTC
7. 1.7 130 km WSW of Adak, Alaska 14:31 UTC
8. 1.9 103 km WSW of Adak, Alaska 13:42 UTC
9. 1.8 92 km WSW of Adak, Alaska 20:01 UTC
10. 3.1 91 km SW of Adak, Alaska 14:47 UTC
11. 2.3 140 km WSW of Adak, Alaska 12:06 UTC
12. 2.1 100 km WSW of Adak, Alaska 03:34 UTC
13. 2.2 132 km WSW of Adak, Alaska 11:52 UTC
14. 1.6 Andreanof Islands, Aleutian Islands, Alaska 02:51 UTC
15. 4.2 140 km WSW of Adak, Alaska 13:48 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 10:24 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.