119 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 it was probably too small to be felt, even directly above it. 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 6.5 on 2018-08-15 — about 1,400,000 times the energy of this one.

Before 2016, the USGS record lists 216 earthquakes of M5 or more within 50 km; the five largest:

1. 7.9 77 km WSW of Adak, Alaska · 45 km NE of this epicentre Jun 10, 1996
2. 7.3 88 km WSW of Adak, Alaska · 33 km NE of this epicentre Jul 7, 1929
3. 7.0 114 km WSW of Adak, Alaska · 26 km NNW of this epicentre Jul 5, 1929
4. 7.0 148 km WSW of Adak, Alaska · 42 km WNW of this epicentre Mar 11, 1957
5. 6.9 151 km WSW of Adak, Alaska · 47 km WNW of this epicentre May 15, 1993

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 51.2411, -178.0259. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.5 158 km WSW of Adak, Alaska 08:55 UTC
2. 2.5 119 km SW of Adak, Alaska 06:56 UTC
3. 2.2 117 km WSW of Adak, Alaska 11:15 UTC
4. 1.7 138 km WSW of Adak, Alaska 02:06 UTC
5. 1.7 124 km WSW of Adak, Alaska 17:37 UTC
6. 1.6 84 km WSW of Adak, Alaska 06:12 UTC
7. 2.8 135 km WSW of Adak, Alaska 06:01 UTC
8. 2.4 110 km WSW of Adak, Alaska 11:32 UTC
9. 2.1 133 km WSW of Adak, Alaska 14:13 UTC
10. 1.9 81 km SW of Adak, Alaska 16:01 UTC
11. 1.5 79 km WSW of Adak, Alaska 13:42 UTC
12. 2.5 103 km SW of Adak, Alaska 19:58 UTC
13. 2.2 106 km WSW of Adak, Alaska 00:25 UTC
14. 2.0 106 km WSW of Adak, Alaska 22:39 UTC
15. 2.5 130 km SW of Adak, Alaska 21:13 UTC

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