120 km SSE of Ugashik, AK

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 1,300 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.1 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 250,000× the energy of this one
2. Mineral, Virginia 2011 M 5.8 11,000× the energy of this one
3. Magna, Utah 2020 M 5.7 7,900× the energy of this one
4. This earthquake M 3.1 about 1,300 lb of TNT
5. Around the size people start to feel M 3.0 this one released 1.4× 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 in our catalogue was M 4.5 on 2017-03-28 — about 130 times the energy of this one.

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 56.6104, -156.3108. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.1 119 km SSE of Ugashik, Alaska 15:56 UTC
2. 2.2 111 km SE of Ugashik, Alaska 03:04 UTC
3. 1.6 77 km SE of Ugashik, Alaska 06:35 UTC
4. 1.8 118 km ENE of Chignik, Alaska 05:19 UTC
5. 1.9 107 km E of Chignik, Alaska 05:38 UTC
6. 1.7 100 km SE of Ugashik, Alaska 05:10 UTC
7. 1.8 102 km SE of Ugashik, Alaska 05:06 UTC
8. 2.7 107 km SSE of Ugashik, Alaska 08:56 UTC
9. 1.8 133 km SW of Akhiok, Alaska 08:44 UTC
10. 2.1 96 km SE of Ugashik, Alaska 21:31 UTC
11. 2.7 122 km E of Chignik, Alaska 08:05 UTC
12. 2.3 101 km SSE of Ugashik, Alaska 06:50 UTC
13. 2.0 135 km SW of Akhiok, Alaska 04:15 UTC
14. 2.2 122 km E of Chignik, Alaska 20:32 UTC
15. 2.2 114 km E of Chignik, Alaska 15:42 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 02:49 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.