106 km SSE of Perryville, 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 2.7 kilotons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 6.5 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 63× the energy of this one
2. Mineral, Virginia 2011 M 5.8 2.8× the energy of this one
3. Magna, Utah 2020 M 5.7 2× the energy of this one
4. This earthquake M 5.5 about 2.7 kilotons of TNT
5. Around the size people start to feel M 3.0 this one released 5,600× 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 55.1016, -158.2373. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.1 98 km SE of Perryville, Alaska 01:40 UTC
2. 2.3 139 km SSE of Perryville, Alaska 01:38 UTC
3. 2.4 124 km SE of Perryville, Alaska 01:20 UTC
4. 2.2 72 km SE of Perryville, Alaska 01:19 UTC
5. 4.7 128 km SSE of Perryville, Alaska 21:00 UTC
6. 2.5 135 km SSE of Perryville, Alaska 20:56 UTC
7. 3.1 136 km SE of Perryville, Alaska 20:42 UTC
8. 2.2 61 km SE of Perryville, Alaska 19:59 UTC
9. 2.0 66 km SE of Perryville, Alaska 19:44 UTC
10. 2.6 125 km SSE of Perryville, Alaska 19:32 UTC
11. 3.0 138 km SSE of Perryville, Alaska 18:37 UTC
12. 2.6 128 km SE of Perryville, Alaska 18:17 UTC
13. 3.2 131 km SSE of Perryville, Alaska 18:14 UTC
14. 2.8 73 km SE of Perryville, Alaska 17:33 UTC
15. 2.8 106 km SSE of Perryville, Alaska 17:22 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 11:06 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 11,000 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.