148 km SE 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 19 km (12 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 5.6 on 2020-07-22 — about 16,000 times the energy of this one.

Before 2016, the USGS record lists 2 earthquakes of M5 or more within 50 km:

1. 6.5 183 km SSE of Perryville, Alaska · 46 km E of this epicentre Jul 1, 1967
2. 5.9 113 km SE of Sand Point, Alaska · 36 km NW of this epicentre Jun 7, 1917

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 54.4317, -158.7946. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 3.1 138 km SSE of Perryville, Alaska 03:09 UTC
2. 2.4 158 km SSE of Sand Point, Alaska 02:25 UTC
3. 2.2 124 km ESE of Sand Point, Alaska 03:40 UTC
4. 2.1 120 km SSE of Perryville, Alaska 00:59 UTC
5. 2.2 168 km SE of Sand Point, Alaska 02:57 UTC
6. 3.1 197 km SE of Sand Point, Alaska 09:10 UTC
7. 3.0 173 km SSE of Perryville, Alaska 08:01 UTC
8. 2.5 south of Alaska 07:43 UTC
9. 2.9 159 km SE of Sand Point, Alaska 09:31 UTC
10. 3.0 129 km SE of Sand Point, Alaska 09:51 UTC
11. 3.1 122 km SSE of Perryville, Alaska 13:10 UTC
12. 1.8 115 km SE of Sand Point, Alaska 18:13 UTC
13. 3.0 145 km SSE of Perryville, Alaska 01:43 UTC
14. 2.2 110 km SE of Sand Point, Alaska 06:37 UTC
15. 1.6 114 km SE of Sand Point, Alaska 01:35 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 15:28 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.