120 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 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 7.6 on 2020-10-19 — about 16,000,000 times the energy of this one.

Before 2016, the USGS record lists 4 earthquakes of M5 or more within 50 km:

1. 6.1 79 km SE of Sand Point, Alaska · 48 km N of this epicentre Nov 14, 1985
2. 5.9 113 km SE of Sand Point, Alaska · 50 km NE of this epicentre Jun 7, 1917
3. 5.9 99 km SE of Sand Point, Alaska · 40 km NNE of this epicentre Oct 20, 1929
4. 5.9 131 km S of Sand Point, Alaska · 42 km WSW 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 54.3238, -159.8197. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.3 100 km SSE of Sand Point, Alaska 02:47 UTC
2. 2.8 87 km SSE of Sand Point, Alaska 15:12 UTC
3. 3.1 97 km SSE of Sand Point, Alaska 19:17 UTC
4. 2.3 132 km SSE of Sand Point, Alaska 16:21 UTC
5. 2.2 104 km SSE of Sand Point, Alaska 15:03 UTC
6. 2.2 113 km SSE of Sand Point, Alaska 23:00 UTC
7. 2.4 107 km SSE of Sand Point, Alaska 16:24 UTC
8. 2.1 99 km SSE of Sand Point, Alaska 00:48 UTC
9. 2.3 102 km SSE of Sand Point, Alaska 04:04 UTC
10. 2.6 111 km SSE of Sand Point, Alaska 19:14 UTC
11. 3.0 106 km SSE of Sand Point, Alaska 15:23 UTC
12. 2.9 107 km SSE of Sand Point, Alaska 06:13 UTC
13. 2.2 109 km SSE of Sand Point, Alaska 00:22 UTC
14. 1.9 114 km SSE of Sand Point, Alaska 08:01 UTC
15. 1.8 100 km SSE of Sand Point, Alaska 02:21 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 18:32 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.