227 km SSE 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, people at rest would likely notice it out to about 25 km (16 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 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 4.4 on 2019-10-26 — about 250 times the energy of this one.

Before 2016, the USGS record lists 6 earthquakes of M5 or more within 50 km; the five largest:

1. 6.3 226 km SSE of False Pass, Alaska · 3 km W of this epicentre Feb 6, 1965
2. 6.3 210 km S of King Cove, Alaska · 24 km NNE of this epicentre Feb 6, 1965
3. 5.7 187 km SSE of False Pass, Alaska · 41 km NW of this epicentre Mar 13, 1965
4. 5.6 203 km SSE of False Pass, Alaska · 39 km WNW of this epicentre Jun 20, 1969
5. 5.4 221 km SSE of False Pass, Alaska · 11 km NNE of this epicentre Jul 2, 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 52.9989, -161.9704. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.7 south of Alaska 20:19 UTC
2. 2.6 207 km SSE of False Pass, Alaska 09:18 UTC
3. 3.3 south of Alaska 13:54 UTC
4. 3.2 218 km SSE of False Pass, Alaska 19:39 UTC
5. 3.0 south of Alaska 18:14 UTC
6. 2.7 south of Alaska 02:44 UTC
7. 3.2 195 km S of King Cove, Alaska 23:40 UTC
8. 3.0 203 km SSE of False Pass, Alaska 16:50 UTC
9. 3.2 235 km SSE of False Pass, Alaska 16:24 UTC
10. 3.0 231 km SSE of False Pass, Alaska 14:40 UTC
11. 2.9 190 km S of King Cove, Alaska 16:51 UTC
12. 3.3 south of Alaska 03:46 UTC
13. 2.6 south of Alaska 12:56 UTC
14. 2.9 south of Alaska 16:03 UTC
15. 3.9 south of Alaska 07:02 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 04:16 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.