152 km E of Atka, Alaska

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

At this magnitude and depth it was probably too small to be felt, even directly above it. 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 120 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.4 would have released about 32 times as much.

1. Mineral, Virginia 2011 M 5.8 130,000× the energy of this one
2. Magna, Utah 2020 M 5.7 89,000× the energy of this one
3. Around the size people start to feel M 3.0 7.9× the energy of this one
4. This earthquake M 2.4 about 120 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 4.5 on 2016-08-14 — about 1,400 times the energy of this one.

Before 2016, the USGS record lists 19 earthquakes of M5 or more within 50 km; the five largest:

1. 7.3 Fox Islands, Aleutian Islands, Alaska · 44 km SSE of this epicentre Jun 24, 2011
2. 6.9 170 km E of Atka, Alaska · 35 km SE of this epicentre Sep 2, 2011
3. 6.3 143 km E of Atka, Alaska · 47 km S of this epicentre Apr 5, 1957
4. 6.2 173 km WSW of Nikolski, Alaska · 46 km ENE of this epicentre Jan 14, 1968
5. 6.1 188 km E of Atka, Alaska · 42 km ESE of this epicentre Jan 4, 1968

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 52.4297, -172.0003. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 3.1 173 km E of Atka, Alaska 01:10 UTC
2. 3.3 129 km ENE of Atka, Alaska 19:41 UTC
3. 3.0 139 km E of Atka, Alaska 07:22 UTC
4. 3.2 173 km E of Atka, Alaska 14:28 UTC
5. 2.8 131 km ENE of Atka, Alaska 15:02 UTC
6. 2.4 163 km E of Atka, Alaska 09:50 UTC
7. 4.1 130 km E of Atka, Alaska 01:21 UTC
8. 3.6 181 km E of Atka, Alaska 16:06 UTC
9. 3.1 181 km E of Atka, Alaska 23:53 UTC
10. 3.0 178 km E of Atka, Alaska 03:47 UTC
11. 3.3 169 km E of Atka, Alaska 22:52 UTC
12. 3.5 159 km ENE of Atka, Alaska 07:46 UTC
13. 3.0 182 km WSW of Nikolski, Alaska 20:52 UTC
14. 2.6 165 km E of Atka, Alaska 23:42 UTC
15. 3.0 162 km E of Atka, Alaska 03:59 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 05:50 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.