138 km SE of Perryville, Alaska

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

How big was it?

This earthquake released about 11 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.9 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 16,000× the energy of this one
2. Mineral, Virginia 2011 M 5.8 710× the energy of this one
3. Magna, Utah 2020 M 5.7 500× the energy of this one
4. This earthquake M 3.9 about 11 tons of TNT
5. Around the size people start to feel M 3.0 this one released 22× 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 55.0240, -157.6143. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 3.5 124 km SE of Perryville, Alaska 09:37 UTC
2. 2.8 134 km SE of Perryville, Alaska 09:35 UTC
3. 4.7 128 km SSE of Chignik, Alaska 09:28 UTC
4. 3.3 143 km SE of Perryville, Alaska 09:07 UTC
5. 3.4 143 km SSE of Chignik, Alaska 08:56 UTC
6. 3.8 142 km SE of Perryville, Alaska 08:55 UTC
7. 3.8 135 km SE of Perryville, Alaska 08:54 UTC
8. 4.1 149 km SSE of Chignik, Alaska 08:40 UTC
9. 3.5 118 km SSE of Chignik, Alaska 08:38 UTC
10. 2.6 126 km SE of Perryville, Alaska 08:38 UTC
11. 3.0 117 km SSE of Perryville, Alaska 08:30 UTC
12. 3.3 122 km SE of Chignik, Alaska 08:24 UTC
13. 3.4 147 km SE of Perryville, Alaska 08:17 UTC
14. 3.2 100 km SE of Perryville, Alaska 08:12 UTC
15. 3.9 142 km SE of Perryville, Alaska 08:02 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 14:38 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 2020-08-18 — it released about 63 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.