94 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 31 km (19 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 1,900 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.2 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 180,000× the energy of this one
2. Mineral, Virginia 2011 M 5.8 7,900× the energy of this one
3. Magna, Utah 2020 M 5.7 5,600× the energy of this one
4. This earthquake M 3.2 about 1,900 lb of TNT
5. Around the size people start to feel M 3.0 this one released 2× 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 4,000,000 times the energy of this one.

Before 2016, the USGS record lists 19 earthquakes of M5 or more within 50 km; the five largest:

1. 7.4 54 km SE of Sand Point, Alaska · 45 km N of this epicentre May 31, 1917
2. 6.6 72 km SE of Sand Point, Alaska · 38 km NNE of this epicentre Oct 16, 1932
3. 6.6 85 km SE of Sand Point, Alaska · 21 km NNE of this epicentre Oct 9, 1985
4. 6.3 68 km SE of Sand Point, Alaska · 42 km N of this epicentre Oct 30, 1932
5. 6.1 79 km SE of Sand Point, Alaska · 18 km N of this epicentre Nov 14, 1985

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 54.5980, -159.7654. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.5 79 km SSE of Sand Point, Alaska 09:19 UTC
2. 2.0 94 km SSE of Sand Point, Alaska 08:34 UTC
3. 2.1 85 km SE of Sand Point, Alaska 08:28 UTC
4. 2.6 105 km SSE of Sand Point, Alaska 09:48 UTC
5. 2.3 104 km SSE of Sand Point, Alaska 07:18 UTC
6. 2.7 103 km SSE of Sand Point, Alaska 21:14 UTC
7. 3.0 132 km SSE of Sand Point, Alaska 15:48 UTC
8. 2.3 84 km SSE of Sand Point, Alaska 02:04 UTC
9. 2.7 86 km SSE of Sand Point, Alaska 02:03 UTC
10. 2.1 124 km SSE of Sand Point, Alaska 23:17 UTC
11. 1.9 64 km SSE of Sand Point, Alaska 05:51 UTC
12. 2.0 88 km SSE of Sand Point, Alaska 03:58 UTC
13. 3.0 116 km SSE of Sand Point, Alaska 14:12 UTC
14. 2.2 107 km SSE of Sand Point, Alaska 04:06 UTC
15. 2.1 87 km SSE of Sand Point, Alaska 23:46 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 18:43 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.