Fox Islands, Aleutian Islands, Alaska

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

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.

Where

Epicentre 51.9456, -170.8004. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.4 137 km SW of Nikolski, Alaska 11:37 UTC
2. 3.3 133 km WSW of Nikolski, Alaska 11:18 UTC
3. 4.6 161 km SW of Nikolski, Alaska 01:34 UTC
4. 3.3 133 km WSW of Nikolski, Alaska 19:37 UTC
5. 3.1 188 km WSW of Nikolski, Alaska 14:13 UTC
6. 3.1 132 km WSW of Nikolski, Alaska 18:15 UTC
7. 3.4 134 km SW of Nikolski, Alaska 05:35 UTC
8. 2.6 140 km SW of Nikolski, Alaska 06:08 UTC
9. 2.6 136 km SW of Nikolski, Alaska 05:47 UTC
10. 2.5 186 km WSW of Nikolski, Alaska 13:19 UTC
11. 2.6 180 km SW of Nikolski, Alaska 10:35 UTC
12. 2.3 179 km SW of Nikolski, Alaska 02:26 UTC
13. 3.5 182 km WSW of Nikolski, Alaska 03:58 UTC
14. 3.1 160 km WSW of Nikolski, Alaska 17:03 UTC
15. 2.4 139 km SW of Nikolski, Alaska 13:34 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 18:35 UTC. QuakeIndex does not forecast aftershocks. When USGS issues an operational aftershock forecast it appears on the USGS event page.

For this area

The largest earthquake within 50 km in our catalogue was M 4.6 on 2016-01-18 — it released about 180 times the energy of this one.

From the QuakeIndex catalogue, built from the USGS FDSN event service.

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.