92 km WSW of Adak, 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 3 km (2 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 6.5 on 2018-08-15 — about 11,000,000 times the energy of this one.

Before 2016, the USGS record lists 198 earthquakes of M5 or more within 50 km; the five largest:

1. 7.9 77 km WSW of Adak, Alaska · 16 km NE of this epicentre Jun 10, 1996
2. 7.3 88 km WSW of Adak, Alaska · 5 km E of this epicentre Jul 7, 1929
3. 7.1 60 km SW of Adak, Alaska · 40 km E of this epicentre Mar 12, 1957
4. 7.0 114 km WSW of Adak, Alaska · 23 km W of this epicentre Jul 5, 1929
5. 7.0 69 km SW of Adak, Alaska · 37 km ESE of this epicentre May 2, 1971

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 51.4825, -177.8206. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 4.0 124 km WSW of Adak, Alaska 19:41 UTC
2. 1.8 111 km WSW of Adak, Alaska 19:37 UTC
3. 1.5 130 km SW of Adak, Alaska 15:06 UTC
4. 1.7 126 km SW of Adak, Alaska 15:33 UTC
5. 3.3 134 km SW of Adak, Alaska 15:31 UTC
6. 4.5 132 km SW of Adak, Alaska 15:26 UTC
7. 3.8 67 km SW of Adak, Alaska 14:31 UTC
8. 1.6 98 km WSW of Adak, Alaska 07:20 UTC
9. 1.9 86 km SW of Adak, Alaska 00:47 UTC
10. 1.5 102 km SW of Adak, Alaska 12:21 UTC
11. 1.6 122 km SW of Adak, Alaska 12:18 UTC
12. 1.6 134 km SW of Adak, Alaska 23:59 UTC
13. 1.5 116 km SW of Adak, Alaska 17:03 UTC
14. 1.7 103 km WSW of Adak, Alaska 04:01 UTC
15. 1.6 105 km WSW of Adak, Alaska 02:12 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 08:12 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.