224 km S of False Pass, 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 69 km (43 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 3.8 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.6 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 45,000× the energy of this one
2. Mineral, Virginia 2011 M 5.8 2,000× the energy of this one
3. Magna, Utah 2020 M 5.7 1,400× the energy of this one
4. This earthquake M 3.6 about 3.8 tons of TNT
5. Around the size people start to feel M 3.0 this one released 7.9× 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 5.0 on 2016-10-01 — about 130 times the energy of this one.

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

1. 6.0 195 km S of False Pass, Alaska · 36 km NW of this epicentre Aug 14, 1924
2. 5.9 228 km S of False Pass, Alaska · 17 km WSW of this epicentre Oct 13, 1972
3. 5.6 203 km SSE of False Pass, Alaska · 33 km NE of this epicentre Jun 20, 1969
4. 5.3 223 km S of False Pass, Alaska · 4 km W of this epicentre Mar 12, 2015
5. 5.0 240 km SSE of False Pass, Alaska · 44 km E of this epicentre Mar 15, 1982

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 52.8667, -162.8443. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.6 211 km SSE of False Pass, Alaska 01:27 UTC
2. 2.7 south of Alaska 20:19 UTC
3. 2.7 193 km S of False Pass, Alaska 20:32 UTC
4. 2.8 237 km S of False Pass, Alaska 19:48 UTC
5. 2.5 246 km S of False Pass, Alaska 20:01 UTC
6. 2.9 208 km S of False Pass, Alaska 14:27 UTC
7. 3.9 Unimak Island region, Alaska 14:00 UTC
8. 2.9 201 km S of False Pass, Alaska 09:58 UTC
9. 2.7 Unimak Island region, Alaska 00:23 UTC
10. 3.0 219 km S of False Pass, Alaska 09:05 UTC
11. 2.7 238 km S of False Pass, Alaska 09:39 UTC
12. 2.9 200 km SSE of False Pass, Alaska 02:24 UTC
13. 3.2 235 km S of False Pass, Alaska 17:56 UTC
14. 3.0 252 km SE of Akutan, Alaska 14:30 UTC
15. 3.0 229 km SE of Akutan, Alaska 12:47 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 02:23 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.