73 km SE 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 189 km (117 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 480 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 6.0 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 350× the energy of this one
2. Mineral, Virginia 2011 M 5.8 16× the energy of this one
3. Magna, Utah 2020 M 5.7 11× the energy of this one
4. This earthquake M 5.0 about 480 tons of TNT
5. Around the size people start to feel M 3.0 this one released 1,000× 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 6.3 on 2016-03-12 — about 89 times the energy of this one.

Before 2016, the USGS record lists 101 earthquakes of M5 or more within 50 km; the five largest:

1. 6.6 62 km SSE of Atka, Alaska · 28 km W of this epicentre Mar 10, 1957
2. 6.5 95 km ESE of Atka, Alaska · 34 km E of this epicentre Mar 10, 1957
3. 6.5 79 km SSE of Atka, Alaska · 11 km SSW of this epicentre Mar 12, 1957
4. 6.5 99 km SE of Atka, Alaska · 31 km E of this epicentre Nov 9, 2015
5. 6.2 79 km SSE of Atka, Alaska · 10 km SSW of this epicentre Mar 22, 1987

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 51.6823, -173.5248. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 3.1 62 km SSE of Atka, Alaska 20:35 UTC
2. 3.2 62 km SSE of Atka, Alaska 18:27 UTC
3. 2.2 73 km ESE of Atka, Alaska 23:31 UTC
4. 2.8 88 km SE of Atka, Alaska 04:20 UTC
5. 3.3 64 km ESE of Atka, Alaska 04:44 UTC
6. 2.9 98 km SSE of Atka, Alaska 15:06 UTC
7. 1.8 46 km SE of Atka, Alaska 16:01 UTC
8. 2.8 102 km SE of Atka, Alaska 12:46 UTC
9. 2.7 113 km SE of Atka, Alaska 09:03 UTC
10. 3.2 63 km SE of Atka, Alaska 16:33 UTC
11. 1.9 45 km ESE of Atka, Alaska 07:31 UTC
12. 2.1 67 km SSE of Atka, Alaska 18:39 UTC
13. 2.2 Andreanof Islands, Aleutian Islands, Alaska 18:09 UTC
14. 1.8 43 km SSE of Atka, Alaska 10:00 UTC
15. 3.1 69 km ESE of Atka, Alaska 14:01 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 08:15 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.