126 km SSW of False Pass, Alaska

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes 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 480 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.8 would have released about 32 times as much.

1. Mineral, Virginia 2011 M 5.8 32,000× the energy of this one
2. Magna, Utah 2020 M 5.7 22,000× the energy of this one
3. Around the size people start to feel M 3.0 2× the energy of this one
4. This earthquake M 2.8 about 480 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 5.7 on 2020-08-13 — about 22,000 times the energy of this one.

Before 2016, the USGS record lists 68 earthquakes of M5 or more within 50 km; the five largest:

1. 6.6 146 km ESE of Akutan, Alaska · 27 km SSE of this epicentre Apr 1, 1946
2. 6.6 92 km SE of Akutan, Alaska · 48 km WSW of this epicentre Feb 19, 2003
3. 6.5 81 km ESE of Akutan, Alaska · 48 km W of this epicentre Feb 6, 1974
4. 6.4 85 km ESE of Akutan, Alaska · 46 km W of this epicentre Nov 20, 1957
5. 6.2 Unimak Island region, Alaska · 2 km NNW of this epicentre Oct 14, 1933

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 53.7645, -163.9450. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.1 110 km ESE of Akutan, Alaska 13:54 UTC
2. 2.1 116 km S of False Pass, Alaska 01:47 UTC
3. 1.9 101 km ESE of Akutan, Alaska 12:53 UTC
4. 2.0 102 km ESE of Akutan, Alaska 10:36 UTC
5. 2.0 142 km S of False Pass, Alaska 04:41 UTC
6. 2.6 141 km SE of Akutan, Alaska 06:02 UTC
7. 3.1 151 km SE of Akutan, Alaska 20:33 UTC
8. 2.8 152 km SE of Akutan, Alaska 19:53 UTC
9. 5.0 151 km SE of Akutan, Alaska 19:27 UTC
10. 3.8 147 km SE of Akutan, Alaska 17:24 UTC
11. 2.8 149 km SE of Akutan, Alaska 16:50 UTC
12. 4.4 145 km SE of Akutan, Alaska 16:31 UTC
13. 2.6 108 km SSW of False Pass, Alaska 23:44 UTC
14. 2.9 108 km SSW of False Pass, Alaska 23:10 UTC
15. 3.2 111 km SSW of False Pass, Alaska 23:04 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 03:35 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.