143 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 680 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.9 would have released about 32 times as much.

1. Mineral, Virginia 2011 M 5.8 22,000× the energy of this one
2. Magna, Utah 2020 M 5.7 16,000× the energy of this one
3. Around the size people start to feel M 3.0 1.4× the energy of this one
4. This earthquake M 2.9 about 680 lb of TNT

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 53.5730, -163.2180. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.4 100 km S of False Pass, Alaska 11:17 UTC
2. 2.6 113 km SSE of False Pass, Alaska 11:12 UTC
3. 2.2 112 km S of False Pass, Alaska 00:32 UTC
4. 2.9 138 km SSE of False Pass, Alaska 08:47 UTC
5. 2.9 102 km SSE of False Pass, Alaska 05:00 UTC
6. 2.8 134 km SSE of False Pass, Alaska 19:01 UTC
7. 2.5 125 km SSE of False Pass, Alaska 12:24 UTC
8. 2.5 108 km SSE of False Pass, Alaska 17:29 UTC
9. 2.4 113 km S of False Pass, Alaska 15:47 UTC
10. 2.9 100 km SSE of False Pass, Alaska 01:27 UTC
11. 2.4 128 km S of False Pass, Alaska 23:53 UTC
12. 2.6 153 km S of False Pass, Alaska 13:38 UTC
13. 3.1 152 km S of False Pass, Alaska 22:31 UTC
14. 2.3 112 km S of False Pass, Alaska 12:24 UTC
15. 2.4 125 km S of False Pass, Alaska 10:12 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 17:00 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 32,000 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.