102 km SSE 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 4 km (2 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 43 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.1 would have released about 32 times as much.

1. Mineral, Virginia 2011 M 5.8 350,000× the energy of this one
2. Magna, Utah 2020 M 5.7 250,000× the energy of this one
3. Around the size people start to feel M 3.0 22× the energy of this one
4. This earthquake M 2.1 about 43 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 5.6 on 2017-04-04 — about 180,000 times the energy of this one.

Before 2016, the USGS record lists 75 earthquakes of M5 or more within 50 km; the five largest:

1. 7.1 75 km S of Adak, Alaska · 49 km WNW of this epicentre Mar 14, 1957
2. 7.0 101 km S of Adak, Alaska · 19 km WSW of this epicentre Sep 9, 1910
3. 6.7 76 km SSE of Adak, Alaska · 26 km NNW of this epicentre Dec 10, 1905
4. 6.2 59 km S of Adak, Alaska · 45 km NW of this epicentre Nov 22, 1950
5. 6.1 106 km SE of Adak, Alaska · 34 km ENE of this epicentre Mar 22, 1927

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 51.0186, -176.0916. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.6 85 km SE of Adak, Alaska 13:03 UTC
2. 2.6 69 km SE of Adak, Alaska 23:16 UTC
3. 3.0 56 km SSE of Adak, Alaska 16:14 UTC
4. 2.1 64 km SSE of Adak, Alaska 07:19 UTC
5. 2.8 78 km SE of Adak, Alaska 17:36 UTC
6. 3.2 79 km SE of Adak, Alaska 05:57 UTC
7. 3.1 74 km SE of Adak, Alaska 05:55 UTC
8. 2.4 105 km SSE of Adak, Alaska 21:29 UTC
9. 1.8 67 km SE of Adak, Alaska 20:40 UTC
10. 1.9 58 km SE of Adak, Alaska 20:10 UTC
11. 1.8 59 km SSE of Adak, Alaska 08:49 UTC
12. 3.1 68 km SE of Adak, Alaska 14:34 UTC
13. 3.0 69 km SE of Adak, Alaska 23:07 UTC
14. 2.1 58 km S of Adak, Alaska 23:49 UTC
15. 2.6 72 km SSE of Adak, Alaska 09:51 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 02:36 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.