169 km W of Adak, 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 85 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.3 would have released about 32 times as much.

1. Mineral, Virginia 2011 M 5.8 180,000× the energy of this one
2. Magna, Utah 2020 M 5.7 130,000× the energy of this one
3. Around the size people start to feel M 3.0 11× the energy of this one
4. This earthquake M 2.3 about 85 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 6.2 on 2017-05-08 — about 710,000 times the energy of this one.

Before 2016, the USGS record lists 23 earthquakes of M5 or more within 50 km; the five largest:

1. 6.6 193 km WSW of Adak, Alaska · 48 km SSW of this epicentre Apr 17, 1954
2. 6.6 174 km W of Adak, Alaska · 6 km SW of this epicentre Apr 16, 2008
3. 6.5 167 km WSW of Adak, Alaska · 46 km S of this epicentre Jan 27, 1943
4. 6.4 187 km W of Adak, Alaska · 19 km WSW of this epicentre Apr 15, 2008
5. 6.3 128 km W of Adak, Alaska · 42 km E of this epicentre May 10, 1939

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 51.9135, -179.0972. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 1.7 201 km W of Adak, Alaska 20:26 UTC
2. 1.9 172 km WSW of Adak, Alaska 03:14 UTC
3. 1.7 133 km W of Adak, Alaska 08:01 UTC
4. 3.1 204 km W of Adak, Alaska 11:45 UTC
5. 2.2 Andreanof Islands, Aleutian Islands, Alaska 14:06 UTC
6. 3.5 189 km W of Adak, Alaska 06:37 UTC
7. 2.2 134 km W of Adak, Alaska 01:47 UTC
8. 2.2 184 km W of Adak, Alaska 01:34 UTC
9. 1.5 172 km W of Adak, Alaska 01:13 UTC
10. 1.6 155 km WSW of Adak, Alaska 01:46 UTC
11. 1.6 154 km W of Adak, Alaska 14:49 UTC
12. 1.8 155 km W of Adak, Alaska 18:40 UTC
13. 2.2 157 km WSW of Adak, Alaska 07:24 UTC
14. 2.1 187 km W of Adak, Alaska 15:34 UTC
15. 2.5 180 km W of Adak, Alaska 15:02 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 11:35 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.