160 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 54.8495, -157.4303. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 3.4 143 km SSE of Chignik, Alaska 08:56 UTC
2. 3.8 142 km SE of Perryville, Alaska 08:55 UTC
3. 3.8 135 km SE of Perryville, Alaska 08:54 UTC
4. 4.1 149 km SSE of Chignik, Alaska 08:40 UTC
5. 2.6 126 km SE of Perryville, Alaska 08:38 UTC
6. 3.4 147 km SE of Perryville, Alaska 08:17 UTC
7. 4.6 155 km SSE of Chignik, Alaska 08:09 UTC
8. 3.9 142 km SE of Perryville, Alaska 08:02 UTC
9. 3.9 135 km SE of Perryville, Alaska 07:58 UTC
10. 3.6 131 km SE of Perryville, Alaska 07:51 UTC
11. 4.4 134 km SSE of Chignik, Alaska 07:50 UTC
12. 3.2 Alaska Peninsula 07:47 UTC
13. 2.8 157 km SE of Perryville, Alaska 07:44 UTC
14. 4.5 154 km SE of Perryville, Alaska 07:32 UTC
15. 4.3 157 km SE of Chignik, Alaska 06:57 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 23:05 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 5.1 on 2020-08-09 — it released about 32 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.