210 km WSW of Adak, 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 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 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 5.1 on 2017-01-18 — about 7,900 times the energy of this one.

Before 2016, the USGS record lists 111 earthquakes of M5 or more within 50 km; the five largest:

1. 6.8 177 km WSW of Adak, Alaska · 50 km NNE of this epicentre Oct 7, 1989
2. 6.7 194 km WSW of Adak, Alaska · 45 km N of this epicentre Sep 12, 1969
3. 6.7 192 km WSW of Adak, Alaska · 39 km N of this epicentre May 24, 1978
4. 6.6 199 km WSW of Adak, Alaska · 38 km NNW of this epicentre Jul 8, 2006
5. 6.5 184 km WSW of Adak, Alaska · 40 km N of this epicentre Dec 8, 1956

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 50.8773, -179.1956. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 1.7 201 km WSW of Adak, Alaska 18:13 UTC
2. 2.1 240 km WSW of Adak, Alaska 18:47 UTC
3. 2.4 225 km WSW of Adak, Alaska 06:21 UTC
4. 3.8 220 km WSW of Adak, Alaska 15:15 UTC
5. 2.1 192 km WSW of Adak, Alaska 03:42 UTC
6. 1.9 215 km WSW of Adak, Alaska 04:17 UTC
7. 2.7 177 km WSW of Adak, Alaska 03:19 UTC
8. 3.4 221 km WSW of Adak, Alaska 02:18 UTC
9. 1.7 195 km WSW of Adak, Alaska 20:13 UTC
10. 1.6 192 km WSW of Adak, Alaska 19:52 UTC
11. 2.5 211 km WSW of Adak, Alaska 19:04 UTC
12. 2.6 220 km WSW of Adak, Alaska 22:36 UTC
13. 3.4 201 km WSW of Adak, Alaska 06:45 UTC
14. 1.8 171 km WSW of Adak, Alaska 04:58 UTC
15. 2.0 216 km WSW of Adak, Alaska 07:42 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 22:05 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.