106 km E of Chignik, Alaska

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage. 1 person has reported feeling it to USGS.

How big was it?

This earthquake released about 11 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.9 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 16,000× the energy of this one
2. Mineral, Virginia 2011 M 5.8 710× the energy of this one
3. Magna, Utah 2020 M 5.7 500× the energy of this one
4. This earthquake M 3.9 about 11 tons of TNT
5. Around the size people start to feel M 3.0 this one released 22× 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 56.1845, -156.6966. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 4.4 114 km E of Chignik, Alaska 18:46 UTC
2. 1.9 111 km E of Chignik, Alaska 14:17 UTC
3. 2.6 115 km E of Chignik, Alaska 08:02 UTC
4. 1.9 95 km E of Chignik, Alaska 01:10 UTC
5. 2.1 114 km E of Chignik, Alaska 21:28 UTC
6. 1.7 82 km E of Chignik, Alaska 10:12 UTC
7. 1.7 118 km SSE of Ugashik, Alaska 05:28 UTC
8. 2.0 81 km E of Chignik, Alaska 01:12 UTC
9. 2.4 110 km ENE of Chignik, Alaska 19:44 UTC
10. 2.1 91 km ESE of Chignik, Alaska 16:55 UTC
11. 2.4 111 km E of Chignik, Alaska 02:47 UTC
12. 2.0 115 km E of Chignik, Alaska 11:04 UTC
13. 2.5 115 km E of Chignik, Alaska 01:40 UTC
14. 2.4 116 km E of Chignik, Alaska 00:56 UTC
15. 1.8 112 km SSE of Ugashik, Alaska 08:51 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 12:07 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 6.9 on 2021-10-11 — 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.