134 km S of Atka, 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 9 km (6 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 5.2 on 2016-04-14 — about 130,000 times the energy of this one.

Before 2016, the USGS record lists 21 earthquakes of M5 or more within 50 km; the five largest:

1. 6.6 89 km S of Atka, Alaska · 48 km NNW of this epicentre Mar 10, 1957
2. 6.1 87 km S of Atka, Alaska · 47 km N of this epicentre Jun 9, 1983
3. 5.8 131 km S of Atka, Alaska · 22 km W of this epicentre Apr 24, 1928
4. 5.5 92 km S of Atka, Alaska · 46 km NNW of this epicentre Sep 5, 2015
5. 5.4 95 km SSE of Atka, Alaska · 48 km NNE of this epicentre Aug 30, 1977

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 50.9889, -174.0756. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 3.1 97 km S of Atka, Alaska 04:33 UTC
2. 2.6 158 km S of Atka, Alaska 23:56 UTC
3. 3.1 153 km S of Atka, Alaska 22:31 UTC
4. 3.1 122 km S of Atka, Alaska 18:34 UTC
5. 2.6 147 km SSE of Atka, Alaska 08:59 UTC
6. 2.5 170 km S of Atka, Alaska 04:24 UTC
7. 2.4 182 km S of Atka, Alaska 16:23 UTC
8. 2.5 102 km S of Atka, Alaska 12:54 UTC
9. 2.4 103 km S of Atka, Alaska 17:28 UTC
10. 2.4 105 km S of Atka, Alaska 15:40 UTC
11. 2.7 137 km SSE of Atka, Alaska 09:51 UTC
12. 2.8 154 km S of Atka, Alaska 13:48 UTC
13. 2.8 162 km SSE of Atka, Alaska 01:04 UTC
14. 3.1 141 km S of Atka, Alaska 19:28 UTC
15. 2.8 180 km S of Atka, Alaska 10:34 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 10:47 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.