152 km SSE of Chignik, Alaska

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage. 1 person has reported feeling it to USGS.

How big was it?

This earthquake released about 5.4 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.7 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 32,000× the energy of this one
2. Mineral, Virginia 2011 M 5.8 1,400× the energy of this one
3. Magna, Utah 2020 M 5.7 1,000× the energy of this one
4. This earthquake M 3.7 about 5.4 tons of TNT
5. Around the size people start to feel M 3.0 this one released 11× 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 55.1606, -157.0446. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 3.3 133 km SE of Perryville, Alaska 12:34 UTC
2. 2.1 142 km SE of Perryville, Alaska 12:28 UTC
3. 3.6 137 km SE of Perryville, Alaska 12:14 UTC
4. 3.6 154 km SE of Perryville, Alaska 12:04 UTC
5. 2.3 120 km SSE of Chignik, Alaska 11:24 UTC
6. 2.3 122 km SE of Chignik, Alaska 10:54 UTC
7. 1.9 139 km SE of Chignik, Alaska 02:51 UTC
8. 2.2 148 km SE of Perryville, Alaska 21:55 UTC
9. 2.6 161 km SE of Chignik, Alaska 21:45 UTC
10. 2.2 141 km SE of Perryville, Alaska 20:22 UTC
11. 3.4 135 km SE of Perryville, Alaska 17:28 UTC
12. 2.7 157 km SE of Chignik, Alaska 06:46 UTC
13. 3.0 144 km SE of Perryville, Alaska 06:02 UTC
14. 2.2 150 km SE of Perryville, Alaska 05:15 UTC
15. 2.4 126 km SE of Chignik, Alaska 05:09 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 11:01 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 5.9 on 2021-07-29 — it released about 2,000 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.