91 km S of Alcan Border, Alaska

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

At this magnitude and depth, people at rest would likely notice it out to about 7 km (4 mi) from the epicentre. Estimated from magnitude, depth and distance with the intensity equation USGS Did You Feel It? uses; felt reports, where there are any, are the measurement.

How big was it?

This earthquake released about 15 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 2.8 would have released about 32 times as much.

1. Mineral, Virginia 2011 M 5.8 1,000,000× the energy of this one
2. Magna, Utah 2020 M 5.7 710,000× the energy of this one
3. Around the size people start to feel M 3.0 63× the energy of this one
4. This earthquake M 1.8 about 15 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.

For this area

The largest earthquake within 50 km since 2016 was M 4.9 on 2021-05-09 — about 45,000 times the energy of this one.

Before 2016, the USGS record lists one earthquake of M5 or more within 50 km:

1. 5.5 87 km ENE of McCarthy, Alaska · 33 km SW of this epicentre Nov 23, 1987

Since 2016: the QuakeIndex catalogue (US, M1.5+), built from the USGS FDSN event service. Before 2016: USGS ComCat, M5+ from 1900. Distances are between epicentres. This is the record, not a forecast.

Where

Epicentre 61.8584, -140.9624. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 1.7 83 km ENE of McCarthy, Alaska 17:15 UTC
2. 1.6 82 km E of McCarthy, Alaska 15:18 UTC
3. 2.4 92 km E of McCarthy, Alaska 16:50 UTC
4. 2.0 85 km E of McCarthy, Alaska 18:43 UTC
5. 2.0 86 km E of McCarthy, Alaska 07:05 UTC
6. 2.1 121 km E of McCarthy, Alaska 05:16 UTC
7. 1.9 87 km E of McCarthy, Alaska 04:16 UTC
8. 2.3 100 km E of McCarthy, Alaska 19:00 UTC
9. 1.6 98 km E of McCarthy, Alaska 09:00 UTC
10. 1.7 81 km ENE of McCarthy, Alaska 13:14 UTC
11. 1.7 113 km E of McCarthy, Alaska 21:17 UTC
12. 1.5 110 km E of McCarthy, Alaska 21:06 UTC
13. 1.7 90 km E of McCarthy, Alaska 02:03 UTC
14. 1.7 86 km ENE of McCarthy, Alaska 11:48 UTC
15. 1.6 79 km ENE of McCarthy, Alaska 11:11 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 17:57 UTC. QuakeIndex does not forecast aftershocks. When USGS issues an operational aftershock forecast it appears on the USGS event page.

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.