146 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 82 km (51 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 7.6 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.8 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 22,000× the energy of this one
2. Mineral, Virginia 2011 M 5.8 1,000× the energy of this one
3. Magna, Utah 2020 M 5.7 710× the energy of this one
4. This earthquake M 3.8 about 7.6 tons of TNT
5. Around the size people start to feel M 3.0 this one released 16× 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 5.9 on 2016-10-27 — about 1,400 times the energy of this one.

Before 2016, the USGS record lists 55 earthquakes of M5 or more within 50 km; the five largest:

1. 8.6 The 1946 Unimak Island, Alaska Earthquake · 27 km ESE of this epicentre Apr 1, 1946
2. 6.6 146 km ESE of Akutan, Alaska · 37 km W of this epicentre Apr 1, 1946
3. 6.2 136 km S of False Pass, Alaska · 37 km WNW of this epicentre Apr 2, 1946
4. 6.2 172 km SSE of False Pass, Alaska · 34 km SE of this epicentre Apr 2, 1946
5. 6.2 184 km SE of Akutan, Alaska · 42 km SSW of this epicentre Apr 6, 1946

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 53.5461, -163.2291. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.2 163 km S of False Pass, Alaska 11:38 UTC
2. 2.4 165 km S of False Pass, Alaska 04:15 UTC
3. 4.2 101 km S of False Pass, Alaska 11:42 UTC
4. 2.5 97 km S of False Pass, Alaska 09:13 UTC
5. 2.5 100 km S of False Pass, Alaska 01:46 UTC
6. 2.4 166 km S of False Pass, Alaska 11:21 UTC
7. 2.3 104 km S of False Pass, Alaska 21:16 UTC
8. 2.5 162 km S of False Pass, Alaska 23:51 UTC
9. 3.9 154 km S of False Pass, Alaska 02:00 UTC
10. 2.5 162 km ESE of Akutan, Alaska 17:16 UTC
11. 3.1 176 km S of False Pass, Alaska 15:58 UTC
12. 2.7 169 km S of False Pass, Alaska 15:36 UTC
13. 3.1 162 km S of False Pass, Alaska 14:39 UTC
14. 2.7 155 km S of False Pass, Alaska 14:18 UTC
15. 4.3 154 km ESE of Akutan, Alaska 22:31 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 23:15 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.