120 km E of Chignik, Alaska

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon.

At this magnitude and depth, people at rest would likely notice it out to about 117 km (73 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 43 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.3 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 4,000× the energy of this one
2. Mineral, Virginia 2011 M 5.8 180× the energy of this one
3. Magna, Utah 2020 M 5.7 130× the energy of this one
4. This earthquake M 4.3 about 43 tons of TNT
5. Around the size people start to feel M 3.0 this one released 89× 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.

For this area

The largest earthquake within 50 km since 2016 was M 6.9 on 2021-10-11 — about 7,900 times the energy of this one.

Before 2016, the USGS record lists 15 earthquakes of M5 or more within 50 km; the five largest:

1. 6.8 117 km SSE of Ugashik, Alaska · 35 km N of this epicentre May 29, 2015
2. 6.4 77 km ESE of Chignik, Alaska · 48 km WSW of this epicentre Mar 24, 1972
3. 6.4 104 km SSE of Ugashik, Alaska · 44 km NNW of this epicentre May 20, 1979
4. 6.3 112 km E of Chignik, Alaska · 14 km SW of this epicentre Feb 25, 1953
5. 6.1 132 km E of Chignik, Alaska · 15 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 56.2790, -156.4660. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.7 117 km SE of Ugashik, Alaska 14:31 UTC
2. 2.3 136 km ESE of Chignik, Alaska 15:19 UTC
3. 1.9 104 km E of Chignik, Alaska 20:09 UTC
4. 1.9 124 km E of Chignik, Alaska 12:36 UTC
5. 2.4 108 km ENE of Chignik, Alaska 16:54 UTC
6. 1.8 141 km ESE of Chignik, Alaska 11:49 UTC
7. 1.7 109 km E of Chignik, Alaska 22:36 UTC
8. 1.8 109 km E of Chignik, Alaska 14:42 UTC
9. 2.2 108 km SSE of Ugashik, Alaska 04:00 UTC
10. 2.5 142 km ESE of Chignik, Alaska 13:46 UTC
11. 2.2 89 km E of Chignik, Alaska 03:57 UTC
12. 1.6 101 km SSE of Ugashik, Alaska 08:29 UTC
13. 2.5 117 km ESE of Chignik, Alaska 14:15 UTC
14. 2.5 114 km E of Chignik, Alaska 18:53 UTC
15. 2.1 114 km E of Chignik, Alaska 17:43 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 00:24 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.