97 km SSW of Atka, Alaska

This was a moderate earthquake. Shaking at this size can damage poorly built structures close to the epicentre.

At this magnitude and depth, people at rest would likely notice it out to about 218 km (135 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 950 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 6.2 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 180× the energy of this one
2. Mineral, Virginia 2011 M 5.8 7.9× the energy of this one
3. Magna, Utah 2020 M 5.7 5.6× the energy of this one
4. This earthquake M 5.2 about 950 tons of TNT
5. Around the size people start to feel M 3.0 this one released 2,000× 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 6.0 on 2016-03-19 — about 16 times the energy of this one.

Before 2016, the USGS record lists 164 earthquakes of M5 or more within 50 km; the five largest:

1. 8.0 1986 Atka, Alaska Earthquake · 19 km NNW of this epicentre May 7, 1986
2. 7.0 101 km SW of Atka, Alaska · 45 km WNW of this epicentre Aug 30, 2013
3. 6.9 100 km ESE of Adak, Alaska · 48 km WNW of this epicentre Oct 13, 1926
4. 6.8 57 km SSW of Atka, Alaska · 40 km NNE of this epicentre Nov 1, 1946
5. 6.8 99 km SW of Atka, Alaska · 38 km WNW of this epicentre Mar 19, 1957

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 51.3651, -174.6461. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.3 50 km SSW of Atka, Alaska 05:41 UTC
2. 2.6 121 km SSW of Atka, Alaska 14:14 UTC
3. 2.4 120 km SSW of Atka, Alaska 06:26 UTC
4. 2.2 66 km SW of Atka, Alaska 05:12 UTC
5. 2.9 117 km SSW of Atka, Alaska 12:53 UTC
6. 3.8 112 km SSW of Atka, Alaska 08:17 UTC
7. 1.9 53 km SSW of Atka, Alaska 01:34 UTC
8. 2.7 118 km SSW of Atka, Alaska 13:30 UTC
9. 3.2 115 km SSW of Atka, Alaska 11:44 UTC
10. 1.8 56 km SSW of Atka, Alaska 12:46 UTC
11. 1.6 57 km SSW of Atka, Alaska 16:36 UTC
12. 3.9 94 km SSW of Atka, Alaska 20:41 UTC
13. 2.3 86 km SSW of Atka, Alaska 04:53 UTC
14. 2.8 83 km S of Atka, Alaska 01:04 UTC
15. 2.1 57 km SW of Atka, Alaska 01:52 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 08:11 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.