Fox Islands, Aleutian Islands, 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 111 km (69 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 30 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.2 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 5,600× the energy of this one
2. Mineral, Virginia 2011 M 5.8 250× the energy of this one
3. Magna, Utah 2020 M 5.7 180× the energy of this one
4. This earthquake M 4.2 about 30 tons of TNT
5. Around the size people start to feel M 3.0 this one released 63× 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 5.2 on 2017-05-19 — about 32 times the energy of this one.

Before 2016, the USGS record lists 76 earthquakes of M5 or more within 50 km; the five largest:

1. 6.6 135 km SW of Nikolski, Alaska · 30 km SSE of this epicentre Dec 23, 1906
2. 6.2 91 km SW of Nikolski, Alaska · 46 km E of this epicentre Feb 10, 1953
3. 6.2 87 km SW of Nikolski, Alaska · 48 km ENE of this epicentre Oct 23, 1957
4. 6.1 88 km SW of Nikolski, Alaska · 42 km ENE of this epicentre Sep 2, 1950
5. 6.0 119 km SSW of Nikolski, Alaska · 45 km ESE of this epicentre Mar 29, 1931

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 52.2116, -170.3289. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.8 161 km SW of Nikolski, Alaska 08:26 UTC
2. 4.5 96 km WSW of Nikolski, Alaska 08:43 UTC
3. 2.6 112 km SW of Nikolski, Alaska 22:01 UTC
4. 3.0 103 km SW of Nikolski, Alaska 11:38 UTC
5. 2.5 116 km SW of Nikolski, Alaska 06:07 UTC
6. 2.9 117 km SW of Nikolski, Alaska 09:48 UTC
7. 3.4 118 km SW of Nikolski, Alaska 00:17 UTC
8. 2.9 162 km SW of Nikolski, Alaska 21:31 UTC
9. 4.0 140 km SW of Nikolski, Alaska 18:22 UTC
10. 3.8 116 km SW of Nikolski, Alaska 15:44 UTC
11. 2.5 172 km SW of Nikolski, Alaska 23:38 UTC
12. 2.6 171 km SW of Nikolski, Alaska 07:27 UTC
13. 2.8 129 km SW of Nikolski, Alaska 22:29 UTC
14. 2.1 131 km SW of Nikolski, Alaska 09:59 UTC
15. 2.1 104 km SW of Nikolski, Alaska 22:52 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 12:13 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.