57 km ESE of Sand Point, Alaska

This was a moderate earthquake. Shaking at this size can damage poorly built structures close to the epicentre.

At this magnitude and depth, people at rest would likely notice it out to about 188 km (117 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 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 6.0 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 350× the energy of this one
2. Mineral, Virginia 2011 M 5.8 16× the energy of this one
3. Magna, Utah 2020 M 5.7 11× the energy of this one
4. This earthquake M 5.0 about 480 tons of TNT
5. Around the size people start to feel M 3.0 this one released 1,000× 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 5.7 on 2020-07-22 — about 11 times the energy of this one.

Before 2016, the USGS record lists 16 earthquakes of M5 or more within 50 km; the five largest:

1. 7.4 54 km SE of Sand Point, Alaska · 29 km SW of this epicentre May 31, 1917
2. 6.6 72 km SE of Sand Point, Alaska · 32 km S of this epicentre Oct 16, 1932
3. 6.6 85 km SE of Sand Point, Alaska · 50 km S of this epicentre Oct 9, 1985
4. 6.5 94 km ESE of Sand Point, Alaska · 42 km SE of this epicentre Feb 14, 1983
5. 6.3 68 km SE of Sand Point, Alaska · 27 km S of this epicentre Oct 30, 1932

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 55.2125, -159.6190. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.3 68 km S of Perryville, Alaska 09:19 UTC
2. 1.8 56 km ESE of Sand Point, Alaska 09:18 UTC
3. 2.1 88 km ESE of Sand Point, Alaska 08:47 UTC
4. 1.9 81 km ESE of Sand Point, Alaska 08:41 UTC
5. 3.2 86 km S of Perryville, Alaska 08:25 UTC
6. 1.9 68 km SE of Sand Point, Alaska 08:11 UTC
7. 1.8 54 km ESE of Sand Point, Alaska 07:58 UTC
8. 1.7 51 km SSE of Sand Point, Alaska 07:44 UTC
9. 1.9 71 km SE of Sand Point, Alaska 07:37 UTC
10. 4.5 80 km S of Perryville, Alaska 07:17 UTC
11. 2.0 81 km ESE of Sand Point, Alaska 06:57 UTC
12. 2.0 78 km S of Ivanof Bay, Alaska 06:40 UTC
13. 2.8 92 km S of Perryville, Alaska 06:36 UTC
14. 2.0 68 km E of Sand Point, Alaska 06:35 UTC
15. 2.9 58 km ESE of Sand Point, Alaska 06:05 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 15:13 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.