82 km W 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 9 km (6 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 5.9 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.5 would have released about 32 times as much.

1. Mineral, Virginia 2011 M 5.8 2,500,000× the energy of this one
2. Magna, Utah 2020 M 5.7 1,800,000× the energy of this one
3. Around the size people start to feel M 3.0 160× the energy of this one
4. This earthquake M 1.5 about 5.9 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 6.2 on 2020-01-23 — about 10,000,000 times the energy of this one.

Before 2016, the USGS record lists 64 earthquakes of M5 or more within 50 km; the five largest:

1. 7.9 77 km WSW of Adak, Alaska · 37 km SSE of this epicentre Jun 10, 1996
2. 7.3 88 km WSW of Adak, Alaska · 44 km S of this epicentre Jul 7, 1929
3. 6.9 78 km WSW of Adak, Alaska · 33 km SSE of this epicentre Mar 20, 1999
4. 6.6 61 km W of Adak, Alaska · 21 km E of this epicentre May 2, 2008
5. 6.5 111 km WSW of Adak, Alaska · 47 km SSW of this epicentre Jun 8, 1996

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 51.8683, -177.8365. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 1.5 84 km WSW of Adak, Alaska 02:19 UTC
2. 2.2 55 km W of Adak, Alaska 15:01 UTC
3. 1.8 74 km WSW of Adak, Alaska 19:26 UTC
4. 1.7 78 km WSW of Adak, Alaska 19:18 UTC
5. 1.6 86 km WSW of Adak, Alaska 08:05 UTC
6. 1.8 89 km WSW of Adak, Alaska 10:28 UTC
7. 1.8 81 km W of Adak, Alaska 20:03 UTC
8. 2.1 81 km W of Adak, Alaska 20:02 UTC
9. 2.0 60 km SW of Adak, Alaska 17:43 UTC
10. 1.9 67 km WSW of Adak, Alaska 13:29 UTC
11. 1.6 72 km SW of Adak, Alaska 07:24 UTC
12. 1.9 84 km SW of Adak, Alaska 00:12 UTC
13. 1.9 112 km WSW of Adak, Alaska 11:52 UTC
14. 1.6 56 km WSW of Adak, Alaska 04:12 UTC
15. 2.0 111 km WSW of Adak, Alaska 10:51 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 07:57 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.