130 km S of Sand Point, 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 25 km (16 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 480 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.8 would have released about 32 times as much.

1. Mineral, Virginia 2011 M 5.8 32,000× the energy of this one
2. Magna, Utah 2020 M 5.7 22,000× the energy of this one
3. Around the size people start to feel M 3.0 2× the energy of this one
4. This earthquake M 2.8 about 480 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 5.8 on 2018-07-19 — about 32,000 times the energy of this one.

Before 2016, the USGS record lists 12 earthquakes of M5 or more within 50 km; the five largest:

1. 6.4 101 km SSW of Sand Point, Alaska · 46 km NW of this epicentre Jul 25, 1917
2. 6.2 141 km SSE of King Cove, Alaska · 38 km WSW of this epicentre Nov 8, 1951
3. 5.9 131 km S of Sand Point, Alaska · 15 km E of this epicentre Dec 3, 1933
4. 5.7 100 km SSW of Sand Point, Alaska · 44 km NW of this epicentre Apr 16, 2010
5. 5.6 84 km S of Sand Point, Alaska · 48 km N of this epicentre May 6, 1924

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 54.1648, -160.6345. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 3.0 118 km S of Sand Point, Alaska 17:52 UTC
2. 2.9 105 km SSW of Sand Point, Alaska 15:22 UTC
3. 2.9 107 km S of Sand Point, Alaska 12:30 UTC
4. 2.3 105 km S of Sand Point, Alaska 22:40 UTC
5. 3.9 121 km S of Sand Point, Alaska 20:07 UTC
6. 2.8 88 km S of Sand Point, Alaska 19:54 UTC
7. 2.4 115 km S of Sand Point, Alaska 19:29 UTC
8. 2.9 129 km S of Sand Point, Alaska 18:27 UTC
9. 2.3 Alaska Peninsula 18:09 UTC
10. 3.0 92 km S of Sand Point, Alaska 16:37 UTC
11. 2.8 96 km SSW of Sand Point, Alaska 15:35 UTC
12. 3.1 85 km SSW of Sand Point, Alaska 13:54 UTC
13. 2.3 123 km S of Sand Point, Alaska 12:44 UTC
14. 2.3 110 km S of Sand Point, Alaska 12:44 UTC
15. 3.0 114 km S of Sand Point, Alaska 12:29 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 11:48 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.