122 km SSE of Atka, 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 96 km (60 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 15 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.0 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 11,000× the energy of this one
2. Mineral, Virginia 2011 M 5.8 500× the energy of this one
3. Magna, Utah 2020 M 5.7 350× the energy of this one
4. This earthquake M 4.0 about 15 tons of TNT
5. Around the size people start to feel M 3.0 this one released 32× 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 5.6 on 2016-03-12 — about 250 times the energy of this one.

Before 2016, the USGS record lists 41 earthquakes of M5 or more within 50 km; the five largest:

1. 6.6 89 km S of Atka, Alaska · 47 km NW of this epicentre Mar 10, 1957
2. 6.1 87 km S of Atka, Alaska · 40 km NW of this epicentre Jun 9, 1983
3. 6.1 93 km SSE of Atka, Alaska · 41 km NNE of this epicentre Nov 26, 2002
4. 5.9 81 km S of Atka, Alaska · 50 km NW of this epicentre May 9, 1986
5. 5.9 93 km SSE of Atka, Alaska · 47 km NNE of this epicentre Jun 24, 1992

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 51.1285, -173.7663. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.5 94 km SSE of Atka, Alaska 16:18 UTC
2. 2.7 107 km SSE of Atka, Alaska 16:11 UTC
3. 1.8 98 km SSE of Atka, Alaska 23:54 UTC
4. 2.1 105 km SE of Atka, Alaska 14:23 UTC
5. 2.0 94 km S of Atka, Alaska 11:22 UTC
6. 3.0 105 km S of Atka, Alaska 13:05 UTC
7. 2.4 82 km SSE of Atka, Alaska 06:55 UTC
8. 2.0 98 km S of Atka, Alaska 00:16 UTC
9. 2.2 91 km S of Atka, Alaska 15:24 UTC
10. 2.4 84 km SSE of Atka, Alaska 00:09 UTC
11. 1.9 108 km SSE of Atka, Alaska 06:43 UTC
12. 2.5 114 km S of Atka, Alaska 20:47 UTC
13. 2.3 128 km S of Atka, Alaska 13:04 UTC
14. 2.2 95 km S of Atka, Alaska 11:25 UTC
15. 1.8 100 km S of Atka, Alaska 02:48 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 07:55 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.