114 km E of Chignik, Alaska

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

At this magnitude and depth, people at rest would likely notice it out to about 18 km (11 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 120 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.4 would have released about 32 times as much.

1. Mineral, Virginia 2011 M 5.8 130,000× the energy of this one
2. Magna, Utah 2020 M 5.7 89,000× the energy of this one
3. Around the size people start to feel M 3.0 7.9× the energy of this one
4. This earthquake M 2.4 about 120 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.

For this area

The largest earthquake within 50 km since 2016 was M 6.9 on 2021-10-11 — about 5,600,000 times the energy of this one.

Before 2016, the USGS record lists 14 earthquakes of M5 or more within 50 km; the five largest:

1. 6.8 117 km SSE of Ugashik, Alaska · 31 km NNE of this epicentre May 29, 2015
2. 6.4 77 km ESE of Chignik, Alaska · 44 km WSW of this epicentre Mar 24, 1972
3. 6.4 104 km SSE of Ugashik, Alaska · 38 km NNW of this epicentre May 20, 1979
4. 6.3 112 km E of Chignik, Alaska · 15 km SSW of this epicentre Feb 25, 1953
5. 6.1 132 km E of Chignik, Alaska · 22 km SE of this epicentre Sep 13, 1911

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 56.3217, -156.5578. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.3 115 km E of Chignik, Alaska 06:52 UTC
2. 2.6 108 km E of Chignik, Alaska 05:24 UTC
3. 1.9 104 km SSE of Ugashik, Alaska 00:15 UTC
4. 1.9 94 km SSE of Ugashik, Alaska 20:44 UTC
5. 2.6 149 km SW of Akhiok, Alaska 04:31 UTC
6. 2.5 103 km ENE of Chignik, Alaska 18:34 UTC
7. 2.3 119 km ENE of Chignik, Alaska 04:51 UTC
8. 2.1 114 km SSE of Ugashik, Alaska 11:39 UTC
9. 2.2 96 km ENE of Chignik, Alaska 10:26 UTC
10. 2.3 117 km SSE of Ugashik, Alaska 12:05 UTC
11. 1.8 103 km ENE of Chignik, Alaska 00:31 UTC
12. 1.8 101 km ENE of Chignik, Alaska 08:38 UTC
13. 2.4 96 km E of Chignik, Alaska 19:48 UTC
14. 2.2 112 km E of Chignik, Alaska 01:21 UTC
15. 2.5 119 km SSE of Ugashik, Alaska 17:28 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 21:19 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.