151 km W of Adak, 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 50 km (31 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 1.4 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.3 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 120,000× the energy of this one
2. Mineral, Virginia 2011 M 5.8 5,400× the energy of this one
3. Magna, Utah 2020 M 5.7 3,800× the energy of this one
4. This earthquake M 3.3 about 1.4 tons of TNT
5. Around the size people start to feel M 3.0 this one released 2.9× 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 6.2 on 2017-05-08 — about 22,000 times the energy of this one.

Before 2016, the USGS record lists 134 earthquakes of M5 or more within 50 km; the five largest:

1. 7.2 162 km WSW of Adak, Alaska · 31 km S of this epicentre Mar 16, 1957
2. 7.0 148 km WSW of Adak, Alaska · 42 km SSE of this epicentre Mar 11, 1957
3. 6.9 151 km WSW of Adak, Alaska · 37 km SSE of this epicentre May 15, 1993
4. 6.8 177 km WSW of Adak, Alaska · 45 km SSW of this epicentre Oct 7, 1989
5. 6.6 187 km WSW of Adak, Alaska · 45 km SW of this epicentre Dec 12, 1944

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 51.6967, -178.8167. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 0.6 150 km W of Adak, Alaska 14:01 UTC
2. 1.5 156 km W of Adak, Alaska 09:31 UTC
3. 1.3 146 km W of Adak, Alaska 08:37 UTC
4. 2.0 133 km WSW of Adak, Alaska 02:20 UTC
5. 1.3 149 km W of Adak, Alaska 16:50 UTC
6. 0.3 149 km W of Adak, Alaska 13:51 UTC
7. 0.1 150 km W of Adak, Alaska 08:16 UTC
8. 0.8 157 km W of Adak, Alaska 01:35 UTC
9. 0.5 143 km W of Adak, Alaska 15:42 UTC
10. 2.2 143 km W of Adak, Alaska 19:11 UTC
11. 2.4 134 km WSW of Adak, Alaska 14:21 UTC
12. 3.4 160 km WSW of Adak, Alaska 16:10 UTC
13. 1.6 126 km W of Adak, Alaska 15:06 UTC
14. 2.6 174 km W of Adak, Alaska 14:05 UTC
15. 2.8 128 km WSW of Adak, Alaska 05:41 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 07:44 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.