134 km SSE of Atka, Alaska

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

At this magnitude and depth, people at rest would likely notice it out to about 20 km (12 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 170 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.5 would have released about 32 times as much.

1. Mineral, Virginia 2011 M 5.8 89,000× the energy of this one
2. Magna, Utah 2020 M 5.7 63,000× the energy of this one
3. Around the size people start to feel M 3.0 5.6× the energy of this one
4. This earthquake M 2.5 about 170 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 5.2 on 2016-04-14 — about 11,000 times the energy of this one.

Before 2016, the USGS record lists 15 earthquakes of M5 or more within 50 km; the five largest:

1. 6.1 87 km S of Atka, Alaska · 50 km NNW of this epicentre Jun 9, 1983
2. 5.8 131 km S of Atka, Alaska · 42 km W of this epicentre Apr 24, 1928
3. 5.8 161 km SSE of Atka, Alaska · 48 km ESE of this epicentre Apr 2, 1957
4. 5.8 165 km SSE of Atka, Alaska · 47 km ESE of this epicentre Apr 2, 1957
5. 5.8 150 km SSE of Atka, Alaska · 49 km E of this epicentre Apr 2, 1957

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 51.0135, -173.7918. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.5 100 km SSE of Atka, Alaska 19:29 UTC
2. 2.5 101 km SSE of Atka, Alaska 00:19 UTC
3. 2.7 178 km S of Atka, Alaska 01:35 UTC
4. 2.8 165 km SSE of Atka, Alaska 05:30 UTC
5. 2.9 169 km S of Atka, Alaska 10:28 UTC
6. 2.7 164 km SSE of Atka, Alaska 04:10 UTC
7. 2.7 151 km S of Atka, Alaska 19:14 UTC
8. 2.1 160 km S of Atka, Alaska 15:03 UTC
9. 2.3 100 km SSE of Atka, Alaska 18:26 UTC
10. 2.9 184 km S of Atka, Alaska 14:56 UTC
11. 2.3 109 km SSE of Atka, Alaska 12:27 UTC
12. 2.0 109 km S of Atka, Alaska 15:50 UTC
13. 2.7 99 km S of Atka, Alaska 12:59 UTC
14. 2.5 125 km S of Atka, Alaska 21:57 UTC
15. 2.1 156 km S of Atka, Alaska 05:33 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 10:05 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.