208 km SW of Nikolski, Alaska

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon.

How big was it?

This earthquake released about 21 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.1 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 7,900× the energy of this one
2. Mineral, Virginia 2011 M 5.8 350× the energy of this one
3. Magna, Utah 2020 M 5.7 250× the energy of this one
4. This earthquake M 4.1 about 21 tons of TNT
5. Around the size people start to feel M 3.0 this one released 45× 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 51.4255, -170.6534. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 3.0 217 km SW of Nikolski, Alaska 14:02 UTC
2. 3.0 200 km SW of Nikolski, Alaska 23:26 UTC
3. 3.3 194 km SW of Nikolski, Alaska 20:12 UTC
4. 3.5 187 km SW of Nikolski, Alaska 20:17 UTC
5. 4.8 186 km SW of Nikolski, Alaska 10:19 UTC
6. 3.2 187 km SW of Nikolski, Alaska 19:46 UTC
7. 4.5 186 km SW of Nikolski, Alaska 17:05 UTC
8. 2.8 238 km ESE of Atka, Alaska 07:53 UTC
9. 2.8 221 km SW of Nikolski, Alaska 13:21 UTC
10. 4.2 217 km SSW of Nikolski, Alaska 15:23 UTC
11. 3.0 158 km SW of Nikolski, Alaska 07:58 UTC
12. 2.9 250 km SSW of Nikolski, Alaska 04:58 UTC
13. 2.6 165 km SSW of Nikolski, Alaska 20:01 UTC
14. 2.9 254 km SSW of Nikolski, Alaska 18:31 UTC
15. 2.9 243 km SSW of Nikolski, Alaska 08:10 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 23:35 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 2017-09-16 — it released about 5.6 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.