146 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 54.9597, -157.5461. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 3.7 131 km SE of Perryville, Alaska 13:37 UTC
2. 2.3 144 km SE of Perryville, Alaska 16:31 UTC
3. 2.8 137 km SSE of Chignik, Alaska 06:54 UTC
4. 2.1 131 km SE of Perryville, Alaska 11:06 UTC
5. 2.1 161 km SE of Perryville, Alaska 05:39 UTC
6. 2.1 161 km SE of Perryville, Alaska 02:25 UTC
7. 2.6 166 km SE of Perryville, Alaska 01:00 UTC
8. 2.0 123 km SE of Perryville, Alaska 00:56 UTC
9. 2.7 144 km SE of Perryville, Alaska 00:54 UTC
10. 3.5 152 km SE of Perryville, Alaska 20:21 UTC
11. 2.7 138 km SE of Perryville, Alaska 11:36 UTC
12. 2.3 132 km SE of Perryville, Alaska 06:24 UTC
13. 2.6 147 km SSE of Chignik, Alaska 15:05 UTC
14. 2.1 143 km SE of Perryville, Alaska 17:48 UTC
15. 2.5 130 km SE of Perryville, Alaska 04:41 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 20:57 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.