120 km SE of Sand Point, Alaska

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon.

At this magnitude and depth, people at rest would likely notice it out to about 101 km (63 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 21 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.1 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 7,900× the energy of this one
2. Mineral, Virginia 2011 M 5.8 350× the energy of this one
3. Magna, Utah 2020 M 5.7 250× the energy of this one
4. This earthquake M 4.1 about 21 tons of TNT
5. Around the size people start to feel M 3.0 this one released 45× more

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 180,000 times the energy of this one.

Before 2016, the USGS record lists 10 earthquakes of M5 or more within 50 km; the five largest:

1. 6.6 72 km SE of Sand Point, Alaska · 48 km NW of this epicentre Oct 16, 1932
2. 6.6 85 km SE of Sand Point, Alaska · 38 km WNW of this epicentre Oct 9, 1985
3. 6.5 94 km ESE of Sand Point, Alaska · 36 km N of this epicentre Feb 14, 1983
4. 6.1 79 km SE of Sand Point, Alaska · 48 km WNW of this epicentre Nov 14, 1985
5. 5.9 113 km SE of Sand Point, Alaska · 10 km W of this epicentre Jun 7, 1917

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 54.6143, -159.0877. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 4.2 99 km SSE of Sand Point, Alaska 06:44 UTC
2. 2.6 124 km SSE of Perryville, Alaska 20:17 UTC
3. 3.0 72 km SE of Sand Point, Alaska 12:29 UTC
4. 2.4 108 km SSE of Sand Point, Alaska 18:04 UTC
5. 2.5 116 km ESE of Sand Point, Alaska 00:01 UTC
6. 2.0 123 km SSE of Perryville, Alaska 04:47 UTC
7. 1.9 113 km SSE of Sand Point, Alaska 10:02 UTC
8. 2.2 85 km ESE of Sand Point, Alaska 17:29 UTC
9. 2.9 96 km SE of Sand Point, Alaska 18:53 UTC
10. 2.5 117 km S of Perryville, Alaska 19:33 UTC
11. 2.0 75 km ESE of Sand Point, Alaska 15:26 UTC
12. 2.7 117 km SSE of Sand Point, Alaska 17:20 UTC
13. 2.9 109 km SSE of Sand Point, Alaska 10:08 UTC
14. 3.2 112 km SSE of Sand Point, Alaska 08:47 UTC
15. 2.6 90 km ESE of Sand Point, Alaska 05:17 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 20:27 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.