63 km SE of Port Graham, Alaska

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

How big was it?

This earthquake released about 30 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.0 would have released about 32 times as much.

1. Mineral, Virginia 2011 M 5.8 500,000× the energy of this one
2. Magna, Utah 2020 M 5.7 350,000× the energy of this one
3. Around the size people start to feel M 3.0 32× the energy of this one
4. This earthquake M 2.0 about 30 lb of TNT

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 58.9841, -150.9807. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 1.6 53 km SSE of Halibut Cove, Alaska 06:35 UTC
2. 2.0 50 km SSE of Halibut Cove, Alaska 10:58 UTC
3. 1.9 48 km SSE of Halibut Cove, Alaska 01:50 UTC
4. 1.6 30 km SE of Seldovia, Alaska 08:26 UTC
5. 1.6 21 km ESE of Port Graham, Alaska 08:28 UTC
6. 1.7 99 km SE of Port Graham, Alaska 03:16 UTC
7. 2.4 94 km SSE of Port Graham, Alaska 02:29 UTC
8. 1.8 73 km SSE of Halibut Cove, Alaska 17:16 UTC
9. 1.6 57 km SSE of Port Graham, Alaska 03:36 UTC
10. 1.8 63 km SE of Port Graham, Alaska 19:19 UTC
11. 1.7 78 km SSE of Port Graham, Alaska 11:08 UTC
12. 1.9 60 km SE of Port Graham, Alaska 10:18 UTC
13. 2.0 Kodiak Island region, Alaska 00:29 UTC
14. 1.8 39 km SE of Seldovia, Alaska 18:53 UTC
15. 3.0 92 km SE of Port Graham, Alaska 18:51 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 09:39 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 4.3 on 2018-07-13 — it released about 2,800 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.