156 km S of False Pass, 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 53.4496, -163.6253. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.8 109 km S of False Pass, Alaska 09:51 UTC
2. 2.0 112 km S of False Pass, Alaska 14:46 UTC
3. 2.6 151 km S of False Pass, Alaska 09:50 UTC
4. 2.0 126 km ESE of Akutan, Alaska 02:06 UTC
5. 2.9 112 km S of False Pass, Alaska 06:33 UTC
6. 2.5 152 km S of False Pass, Alaska 16:46 UTC
7. 4.3 115 km SSW of False Pass, Alaska 02:59 UTC
8. 2.3 164 km S of False Pass, Alaska 21:58 UTC
9. 2.7 Unimak Island region, Alaska 00:23 UTC
10. 2.5 Unimak Island region, Alaska 06:26 UTC
11. 2.3 129 km S of False Pass, Alaska 13:22 UTC
12. 4.3 145 km S of False Pass, Alaska 19:56 UTC
13. 2.6 181 km S of False Pass, Alaska 17:43 UTC
14. 3.1 170 km S of False Pass, Alaska 02:44 UTC
15. 3.0 Unimak Island region, Alaska 02:34 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 17:24 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 5.9 on 2016-10-27 — it released about 11,000 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.