150 km SW of Nikolski, 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 95 km (59 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 5.1 on 2017-03-14 — about 45 times the energy of this one.

Before 2016, the USGS record lists 78 earthquakes of M5 or more within 50 km; the five largest:

1. 6.6 135 km SW of Nikolski, Alaska · 33 km ESE of this epicentre Dec 23, 1906
2. 6.2 179 km SW of Nikolski, Alaska · 33 km SSW of this epicentre Jun 4, 1956
3. 6.2 Fox Islands, Aleutian Islands, Alaska · 49 km SSW of this epicentre Mar 10, 1957
4. 6.1 Fox Islands, Aleutian Islands, Alaska · 35 km SW of this epicentre Jan 11, 1961
5. 6.0 128 km SW of Nikolski, Alaska · 24 km ENE of this epicentre Jun 1, 1945

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 52.0676, -170.5577. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 3.7 123 km SW of Nikolski, Alaska 08:22 UTC
2. 4.8 145 km SW of Nikolski, Alaska 08:00 UTC
3. 4.4 137 km SW of Nikolski, Alaska 07:39 UTC
4. 4.9 137 km SW of Nikolski, Alaska 08:23 UTC
5. 2.9 173 km WSW of Nikolski, Alaska 19:03 UTC
6. 2.7 136 km SW of Nikolski, Alaska 09:03 UTC
7. 3.4 129 km SW of Nikolski, Alaska 11:21 UTC
8. 3.6 131 km SW of Nikolski, Alaska 07:33 UTC
9. 3.6 180 km SW of Nikolski, Alaska 09:59 UTC
10. 2.9 135 km WSW of Nikolski, Alaska 19:39 UTC
11. 2.4 137 km SW of Nikolski, Alaska 11:37 UTC
12. 3.3 133 km WSW of Nikolski, Alaska 11:18 UTC
13. 4.6 161 km SW of Nikolski, Alaska 01:34 UTC
14. 3.3 133 km WSW of Nikolski, Alaska 19:37 UTC
15. 3.1 132 km WSW of Nikolski, Alaska 18:15 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 10:43 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.