81 km SE of Atka, 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 7 km (4 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 5.4 on 2017-06-17 — about 11,000 times the energy of this one.

Before 2016, the USGS record lists 85 earthquakes of M5 or more within 50 km; the five largest:

1. 6.6 62 km SSE of Atka, Alaska · 49 km WSW of this epicentre Mar 10, 1957
2. 6.5 95 km ESE of Atka, Alaska · 14 km ESE of this epicentre Mar 10, 1957
3. 6.5 79 km SSE of Atka, Alaska · 31 km SW of this epicentre Mar 12, 1957
4. 6.5 99 km SE of Atka, Alaska · 18 km SE of this epicentre Nov 9, 2015
5. 6.2 79 km SSE of Atka, Alaska · 30 km SW of this epicentre Mar 22, 1987

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 51.7617, -173.2368. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.8 101 km SSE of Atka, Alaska 05:59 UTC
2. 3.2 93 km SSE of Atka, Alaska 03:36 UTC
3. 3.6 103 km SE of Atka, Alaska 03:16 UTC
4. 2.9 106 km ESE of Atka, Alaska 20:44 UTC
5. 3.3 112 km SE of Atka, Alaska 06:50 UTC
6. 3.2 72 km ESE of Atka, Alaska 21:38 UTC
7. 3.0 90 km SSE of Atka, Alaska 14:03 UTC
8. 2.3 52 km SE of Atka, Alaska 21:54 UTC
9. 1.6 40 km ESE of Atka, Alaska 04:32 UTC
10. 3.0 57 km ESE of Atka, Alaska 00:52 UTC
11. 3.0 71 km ESE of Atka, Alaska 10:26 UTC
12. 2.8 92 km SE of Atka, Alaska 03:48 UTC
13. 3.9 45 km SE of Atka, Alaska 08:05 UTC
14. 2.1 54 km ESE of Atka, Alaska 10:18 UTC
15. 3.5 39 km ESE of Atka, Alaska 02:57 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 06:35 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.