155 km SE of Atka, Alaska

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

At this magnitude and depth it was probably too small to be felt, even directly above it. 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 4.2 on 2019-03-17 — about 130 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. 6.1 108 km SE of Atka, Alaska · 49 km NW of this epicentre May 1, 1933
2. 6.1 109 km SE of Atka, Alaska · 47 km NW of this epicentre Jul 17, 1985
3. 6.0 130 km ESE of Atka, Alaska · 48 km N of this epicentre Oct 1, 1960
4. 6.0 107 km SE of Atka, Alaska · 49 km WNW of this epicentre Feb 1, 1971
5. 5.9 106 km SE of Atka, Alaska · 49 km WNW of this epicentre Mar 14, 2002

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 51.2919, -172.4880. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.7 145 km SE of Atka, Alaska 06:18 UTC
2. 3.1 173 km ESE of Atka, Alaska 12:01 UTC
3. 3.2 147 km SE of Atka, Alaska 00:41 UTC
4. 2.9 120 km SE of Atka, Alaska 16:30 UTC
5. 2.2 158 km SSE of Atka, Alaska 11:51 UTC
6. 2.4 189 km SE of Atka, Alaska 09:29 UTC
7. 3.1 169 km ESE of Atka, Alaska 05:02 UTC
8. 2.9 168 km SE of Atka, Alaska 02:00 UTC
9. 2.9 112 km SE of Atka, Alaska 15:01 UTC
10. 3.5 171 km ESE of Atka, Alaska 17:33 UTC
11. 3.1 132 km ESE of Atka, Alaska 19:43 UTC
12. 4.1 155 km ESE of Atka, Alaska 10:00 UTC
13. 3.9 139 km SE of Atka, Alaska 19:20 UTC
14. 3.3 133 km ESE of Atka, Alaska 17:46 UTC
15. 3.0 127 km SE of Atka, Alaska 17:36 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.