107 km SE of Perryville, 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 55.2960, -157.8380. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.4 124 km SE of Perryville, Alaska 01:20 UTC
2. 2.2 72 km SE of Perryville, Alaska 01:19 UTC
3. 2.7 150 km SE of Perryville, Alaska 01:16 UTC
4. 2.7 128 km SE of Perryville, Alaska 00:21 UTC
5. 2.6 146 km SE of Perryville, Alaska 00:10 UTC
6. 2.7 138 km SE of Perryville, Alaska 00:05 UTC
7. 2.8 146 km SE of Perryville, Alaska 22:25 UTC
8. 4.7 128 km SSE of Perryville, Alaska 21:00 UTC
9. 2.5 135 km SSE of Perryville, Alaska 20:56 UTC
10. 3.1 136 km SE of Perryville, Alaska 20:42 UTC
11. 3.1 91 km SSE of Chignik, Alaska 20:23 UTC
12. 2.6 128 km SE of Perryville, Alaska 18:17 UTC
13. 2.8 73 km SE of Perryville, Alaska 17:33 UTC
14. 3.2 113 km ESE of Perryville, Alaska 16:59 UTC
15. 2.7 139 km SE of Perryville, Alaska 15:27 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 15:53 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 8.2 on 2021-07-29 — it released about 1,400,000 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.