190 km S of Atka, Alaska

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

At this magnitude and depth, people at rest would likely notice it out to about 75 km (47 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 5.4 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.7 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 32,000× the energy of this one
2. Mineral, Virginia 2011 M 5.8 1,400× the energy of this one
3. Magna, Utah 2020 M 5.7 1,000× the energy of this one
4. This earthquake M 3.7 about 5.4 tons of TNT
5. Around the size people start to feel M 3.0 this one released 11× 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 4.5 on 2017-01-10 — about 16 times the energy of this one.

Before 2016, the USGS record lists 5 earthquakes of M5 or more within 50 km:

1. 6.6 208 km S of Atka, Alaska · 49 km WSW of this epicentre Apr 30, 1913
2. 6.0 234 km SSE of Atka, Alaska · 44 km SSE of this epicentre Nov 9, 1929
3. 5.6 198 km SSE of Atka, Alaska · 28 km E of this epicentre Mar 7, 2015
4. 5.4 198 km SSE of Atka, Alaska · 10 km SE of this epicentre Feb 20, 2013
5. 5.2 181 km SSE of Atka, Alaska · 50 km ENE of this epicentre Oct 12, 2006

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 50.5141, -173.6903. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 3.0 208 km S of Atka, Alaska 22:11 UTC
2. 3.1 162 km SSE of Atka, Alaska 06:43 UTC
3. 2.9 204 km SSE of Atka, Alaska 22:38 UTC
4. 3.3 150 km SSE of Atka, Alaska 11:18 UTC
5. 2.3 226 km SSE of Atka, Alaska 09:39 UTC
6. 2.3 143 km S of Atka, Alaska 11:20 UTC
7. 3.5 209 km SSE of Atka, Alaska 06:15 UTC
8. 4.4 213 km SSE of Atka, Alaska 09:52 UTC
9. 3.9 221 km SSE of Atka, Alaska 08:55 UTC
10. 2.3 159 km S of Atka, Alaska 22:14 UTC
11. 2.5 201 km SSE of Atka, Alaska 17:52 UTC
12. 4.0 209 km SSE of Atka, Alaska 17:37 UTC
13. 3.4 204 km SSE of Atka, Alaska 19:38 UTC
14. 2.9 178 km S of Atka, Alaska 11:16 UTC
15. 2.7 203 km SSE of Atka, Alaska 09:15 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 17:19 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.