159 km SW 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 20 km (12 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 120 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.4 would have released about 32 times as much.

1. Mineral, Virginia 2011 M 5.8 130,000× the energy of this one
2. Magna, Utah 2020 M 5.7 89,000× the energy of this one
3. Around the size people start to feel M 3.0 7.9× the energy of this one
4. This earthquake M 2.4 about 120 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 6.0 on 2019-12-02 — about 250,000 times the energy of this one.

Before 2016, the USGS record lists 115 earthquakes of M5 or more within 50 km; the five largest:

1. 7.0 148 km WSW of Adak, Alaska · 44 km NNW of this epicentre Mar 11, 1957
2. 6.9 151 km WSW of Adak, Alaska · 49 km NNW of this epicentre May 15, 1993
3. 6.8 111 km SW of Adak, Alaska · 48 km NE of this epicentre Jan 4, 1912
4. 6.6 117 km SW of Adak, Alaska · 44 km NE of this epicentre Sep 30, 1992
5. 6.5 144 km SW of Adak, Alaska · 16 km NE of this epicentre Apr 16, 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 50.9650, -178.4110. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.5 154 km WSW of Adak, Alaska 19:48 UTC
2. 2.6 122 km WSW of Adak, Alaska 22:54 UTC
3. 2.8 154 km WSW of Adak, Alaska 21:54 UTC
4. 3.6 147 km WSW of Adak, Alaska 21:52 UTC
5. 2.1 124 km WSW of Adak, Alaska 20:47 UTC
6. 2.6 139 km SW of Adak, Alaska 13:36 UTC
7. 2.5 152 km SW of Adak, Alaska 11:24 UTC
8. 2.7 161 km WSW of Adak, Alaska 06:15 UTC
9. 2.4 129 km SW of Adak, Alaska 23:28 UTC
10. 2.6 149 km WSW of Adak, Alaska 12:33 UTC
11. 3.5 160 km SW of Adak, Alaska 15:33 UTC
12. 2.9 118 km SW of Adak, Alaska 09:08 UTC
13. 2.6 147 km SW of Adak, Alaska 09:33 UTC
14. 3.2 166 km SW of Adak, Alaska 09:29 UTC
15. 2.5 132 km WSW of Adak, Alaska 00:12 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 11:15 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.