145 km SE of Sand Point, Alaska

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

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.

Where

Epicentre 54.4631, -158.8070. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.5 116 km ESE of Sand Point, Alaska 00:01 UTC
2. 2.0 123 km SSE of Perryville, Alaska 04:47 UTC
3. 2.5 117 km S of Perryville, Alaska 19:33 UTC
4. 3.3 160 km SE of Sand Point, Alaska 10:49 UTC
5. 2.3 128 km SSE of Perryville, Alaska 13:17 UTC
6. 2.9 142 km SSE of Perryville, Alaska 06:34 UTC
7. 4.1 120 km SE of Sand Point, Alaska 18:59 UTC
8. 2.2 114 km SE of Sand Point, Alaska 15:40 UTC
9. 2.5 130 km SSE of Perryville, Alaska 09:11 UTC
10. 2.8 101 km SE of Sand Point, Alaska 22:03 UTC
11. 2.8 159 km SE of Sand Point, Alaska 04:17 UTC
12. 2.2 149 km SE of Sand Point, Alaska 03:59 UTC
13. 3.0 157 km SE of Sand Point, Alaska 18:01 UTC
14. 2.6 162 km SE of Sand Point, Alaska 01:30 UTC
15. 4.1 152 km SE of Sand Point, Alaska 01:14 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 17:27 UTC. QuakeIndex does not forecast aftershocks. When USGS issues an operational aftershock forecast it appears on the USGS event page.

For this area

The largest earthquake within 50 km in our catalogue was M 5.6 on 2020-07-22 — it released about 4,000 times the energy of this one.

From the QuakeIndex catalogue, built from the USGS FDSN event service.

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.