129 km SE 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 18 km (11 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 950 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.0 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 350,000× the energy of this one
2. Mineral, Virginia 2011 M 5.8 16,000× the energy of this one
3. Magna, Utah 2020 M 5.7 11,000× the energy of this one
4. This earthquake M 3.0 about 950 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 6.1 on 2020-07-22 — about 45,000 times the energy of this one.

Before 2016, the USGS record lists 7 earthquakes of M5 or more within 50 km; the five largest:

1. 6.6 85 km SE of Sand Point, Alaska · 45 km WNW of this epicentre Oct 9, 1985
2. 6.5 94 km ESE of Sand Point, Alaska · 44 km NNW of this epicentre Feb 14, 1983
3. 5.9 113 km SE of Sand Point, Alaska · 17 km WNW of this epicentre Jun 7, 1917
4. 5.9 99 km SE of Sand Point, Alaska · 35 km WNW of this epicentre Oct 20, 1929
5. 5.9 90 km ESE of Sand Point, Alaska · 49 km NNW of this epicentre Feb 14, 1983

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 54.5485, -159.0142. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.4 146 km SE of Sand Point, Alaska 01:22 UTC
2. 2.5 125 km SE of Sand Point, Alaska 15:01 UTC
3. 4.3 150 km SE of Sand Point, Alaska 14:30 UTC
4. 3.2 176 km SE of Sand Point, Alaska 22:06 UTC
5. 2.7 118 km SE of Sand Point, Alaska 04:39 UTC
6. 3.2 145 km SE of Sand Point, Alaska 11:49 UTC
7. 2.8 149 km SE of Sand Point, Alaska 10:37 UTC
8. 3.2 146 km SE of Sand Point, Alaska 21:39 UTC
9. 2.7 155 km SE of Sand Point, Alaska 18:42 UTC
10. 3.6 148 km SE of Sand Point, Alaska 18:37 UTC
11. 3.6 159 km SE of Sand Point, Alaska 02:46 UTC
12. 3.0 104 km ESE of Sand Point, Alaska 08:06 UTC
13. 2.6 93 km ESE of Sand Point, Alaska 12:59 UTC
14. 2.8 87 km SE of Sand Point, Alaska 08:37 UTC
15. 3.2 114 km SE of Sand Point, Alaska 11:53 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 13:32 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.