98 km SSE of Sand Point, 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 1 km (1 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 7.6 on 2020-10-19 — about 16,000,000 times the energy of this one.

Before 2016, the USGS record lists 14 earthquakes of M5 or more within 50 km; the five largest:

1. 6.6 85 km SE of Sand Point, Alaska · 40 km NE of this epicentre Oct 9, 1985
2. 6.1 79 km SE of Sand Point, Alaska · 32 km NNE of this epicentre Nov 14, 1985
3. 6.0 71 km SSE of Sand Point, Alaska · 30 km N of this epicentre Jun 27, 1918
4. 5.9 99 km SE of Sand Point, Alaska · 36 km ENE of this epicentre Oct 20, 1929
5. 5.9 131 km S of Sand Point, Alaska · 45 km SSW of this epicentre Dec 3, 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 54.4994, -160.0237. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 1.9 87 km SSE of Sand Point, Alaska 08:05 UTC
2. 1.8 90 km SSE of Sand Point, Alaska 08:04 UTC
3. 1.7 86 km SSE of Sand Point, Alaska 08:04 UTC
4. 2.2 107 km SSE of Sand Point, Alaska 08:02 UTC
5. 1.9 89 km S of Sand Point, Alaska 08:02 UTC
6. 2.5 96 km S of Sand Point, Alaska 07:59 UTC
7. 2.4 92 km S of Sand Point, Alaska 07:58 UTC
8. 1.9 80 km S of Sand Point, Alaska 07:58 UTC
9. 3.1 90 km SSE of Sand Point, Alaska 07:56 UTC
10. 2.9 93 km SSE of Sand Point, Alaska 07:56 UTC
11. 1.6 81 km S of Sand Point, Alaska 07:55 UTC
12. 2.7 94 km SSE of Sand Point, Alaska 07:54 UTC
13. 2.2 86 km S of Sand Point, Alaska 07:53 UTC
14. 2.0 85 km S of Sand Point, Alaska 07:52 UTC
15. 1.9 83 km S of Sand Point, Alaska 07:51 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 23:40 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.