102 km SE of Old Harbor, 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 56.4828, -152.2612. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 3.2 124 km SE of Old Harbor, Alaska 15:20 UTC
2. 3.3 127 km SE of Old Harbor, Alaska 13:48 UTC
3. 2.6 120 km SSE of Old Harbor, Alaska 11:57 UTC
4. 4.9 128 km SE of Old Harbor, Alaska 11:45 UTC
5. 2.2 78 km SSE of Old Harbor, Alaska 11:40 UTC
6. 2.8 119 km SE of Old Harbor, Alaska 11:26 UTC
7. 3.3 Kodiak Island region, Alaska 11:21 UTC
8. 3.2 119 km SE of Old Harbor, Alaska 11:16 UTC
9. 3.1 123 km SE of Old Harbor, Alaska 11:15 UTC
10. 4.6 116 km SE of Old Harbor, Alaska 11:08 UTC
11. 4.7 134 km SSE of Old Harbor, Alaska 11:07 UTC
12. 5.6 133 km SE of Old Harbor, Alaska 11:02 UTC
13. 1.7 64 km SE of Old Harbor, Alaska 08:59 UTC
14. 2.7 76 km SE of Old Harbor, Alaska 11:05 UTC
15. 2.5 92 km SSE of Old Harbor, Alaska 21:43 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 12:39 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 5.4 on 2017-05-11 — it released about 89 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.