209 km SSE of Unalaska, 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 23 km (14 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 340 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.7 would have released about 32 times as much.

1. Mineral, Virginia 2011 M 5.8 45,000× the energy of this one
2. Magna, Utah 2020 M 5.7 32,000× the energy of this one
3. Around the size people start to feel M 3.0 2.8× the energy of this one
4. This earthquake M 2.7 about 340 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 2019-08-03 — about 5,600 times the energy of this one.

Before 2016, the USGS record lists 8 earthquakes of M5 or more within 50 km; the five largest:

1. 7.0 203 km SSE of Unalaska, Alaska · 26 km ENE of this epicentre Aug 22, 1940
2. 6.5 183 km S of Unalaska, Alaska · 41 km WNW of this epicentre Apr 19, 1957
3. 6.0 221 km S of Unalaska, Alaska · 17 km SSW of this epicentre Mar 17, 1957
4. 6.0 218 km SE of Nikolski, Alaska · 46 km SW of this epicentre Aug 7, 2004
5. 5.4 214 km ESE of Nikolski, Alaska · 30 km WSW of this epicentre Apr 8, 1975

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 52.0426, -165.8369. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.9 184 km SSE of Unalaska, Alaska 01:33 UTC
2. 2.7 189 km SSE of Unalaska, Alaska 06:55 UTC
3. 2.4 204 km SE of Nikolski, Alaska 00:41 UTC
4. 2.5 224 km SE of Nikolski, Alaska 16:33 UTC
5. 3.1 193 km SSE of Unalaska, Alaska 08:34 UTC
6. 2.6 189 km SSE of Unalaska, Alaska 23:18 UTC
7. 2.8 199 km SSE of Unalaska, Alaska 14:34 UTC
8. 2.8 189 km SSE of Unalaska, Alaska 11:42 UTC
9. 2.9 197 km S of Unalaska, Alaska 12:53 UTC
10. 2.6 189 km SSE of Unalaska, Alaska 07:16 UTC
11. 2.4 184 km SSE of Unalaska, Alaska 08:45 UTC
12. 2.9 190 km S of Unalaska, Alaska 01:51 UTC
13. 2.6 209 km S of Unalaska, Alaska 17:43 UTC
14. 3.4 195 km S of Unalaska, Alaska 23:49 UTC
15. 2.6 203 km ESE of Nikolski, Alaska 07:44 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 09:41 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.