185 km SW of Nikolski, Alaska

This was a moderate earthquake. Shaking at this size can damage poorly built structures close to the epicentre. 3 people have reported feeling it to USGS.

How big was it?

This earthquake released about 950 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 6.2 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 180× the energy of this one
2. Mineral, Virginia 2011 M 5.8 7.9× the energy of this one
3. Magna, Utah 2020 M 5.7 5.6× the energy of this one
4. This earthquake M 5.2 about 950 tons of TNT
5. Around the size people start to feel M 3.0 this one released 2,000× 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 51.9831, -171.1001. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 3.5 160 km SW of Nikolski, Alaska 23:35 UTC
2. 3.1 137 km SW of Nikolski, Alaska 10:52 UTC
3. 2.7 172 km SW of Nikolski, Alaska 00:30 UTC
4. 2.8 162 km SW of Nikolski, Alaska 11:46 UTC
5. 4.1 138 km SW of Nikolski, Alaska 09:51 UTC
6. 3.4 185 km E of Atka, Alaska 16:58 UTC
7. 3.5 159 km WSW of Nikolski, Alaska 17:22 UTC
8. 3.2 169 km WSW of Nikolski, Alaska 00:38 UTC
9. 2.8 182 km WSW of Nikolski, Alaska 15:34 UTC
10. 4.6 185 km WSW of Nikolski, Alaska 21:21 UTC
11. 3.4 182 km E of Atka, Alaska 08:35 UTC
12. 3.6 178 km WSW of Nikolski, Alaska 23:30 UTC
13. 4.4 Fox Islands, Aleutian Islands, Alaska 14:04 UTC
14. 2.5 172 km SW of Nikolski, Alaska 21:44 UTC
15. 3.0 168 km SW of Nikolski, Alaska 20:41 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 16:04 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 5.9 on 2018-08-25 — it released about 11 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.