185 km SSE of Akhiok, 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 55.5666, -152.4982. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 3.0 188 km SSE of Old Harbor, Alaska 00:48 UTC
2. 2.4 146 km SSE of Old Harbor, Alaska 07:49 UTC
3. 2.4 203 km SSE of Old Harbor, Alaska 02:30 UTC
4. 2.5 192 km SSE of Akhiok, Alaska 12:56 UTC
5. 2.5 163 km SSE of Old Harbor, Alaska 16:44 UTC
6. 2.7 167 km SSE of Old Harbor, Alaska 04:15 UTC
7. 2.4 205 km SSE of Akhiok, Alaska 11:28 UTC
8. 2.9 south of Alaska 09:59 UTC
9. 2.9 159 km SSE of Old Harbor, Alaska 15:59 UTC
10. 2.7 186 km SSE of Old Harbor, Alaska 04:10 UTC
11. 2.6 234 km SSE of Akhiok, Alaska 12:10 UTC
12. 2.7 163 km SSE of Old Harbor, Alaska 00:52 UTC
13. 2.9 175 km SE of Akhiok, Alaska 22:56 UTC
14. 2.7 215 km SSE of Old Harbor, Alaska 04:37 UTC
15. 2.4 183 km SSE of Akhiok, Alaska 05:53 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 20:13 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 4.4 on 2017-09-05 — it released about 5.6 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.