158 km SSE 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 11 km (7 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 950 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.0 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 350,000× the energy of this one
2. Mineral, Virginia 2011 M 5.8 16,000× the energy of this one
3. Magna, Utah 2020 M 5.7 11,000× the energy of this one
4. This earthquake M 3.0 about 950 lb of TNT

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 2019-02-15 — about 1,400 times the energy of this one.

Before 2016, the USGS record lists 21 earthquakes of M5 or more within 50 km; the five largest:

1. 8.6 The 1946 Unimak Island, Alaska Earthquake · 8 km W of this epicentre Apr 1, 1946
2. 6.2 172 km SSE of False Pass, Alaska · 20 km SSW of this epicentre Apr 2, 1946
3. 6.1 166 km S of False Pass, Alaska · 31 km WSW of this epicentre Oct 14, 1929
4. 6.0 137 km S of False Pass, Alaska · 40 km WNW of this epicentre May 22, 1988
5. 5.7 187 km SSE of False Pass, Alaska · 33 km SE of this epicentre Mar 13, 1965

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 53.4950, -162.7041. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.6 150 km S of False Pass, Alaska 06:41 UTC
2. 3.6 160 km SSE of False Pass, Alaska 18:10 UTC
3. 2.8 158 km SSE of False Pass, Alaska 10:11 UTC
4. 2.6 111 km SSE of False Pass, Alaska 22:09 UTC
5. 4.6 151 km S of False Pass, Alaska 15:25 UTC
6. 2.4 150 km S of False Pass, Alaska 18:32 UTC
7. 2.3 111 km SSE of False Pass, Alaska 19:33 UTC
8. 2.6 157 km S of False Pass, Alaska 23:31 UTC
9. 2.8 122 km SSE of False Pass, Alaska 14:31 UTC
10. 2.8 143 km SSE of False Pass, Alaska 15:46 UTC
11. 2.4 115 km S of False Pass, Alaska 22:36 UTC
12. 3.3 124 km SSE of False Pass, Alaska 09:53 UTC
13. 2.5 139 km SSE of False Pass, Alaska 06:04 UTC
14. 3.0 Unimak Island region, Alaska 21:20 UTC
15. 2.5 144 km SSE of False Pass, Alaska 21:41 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 23:53 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.