138 km W 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 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 240 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.6 would have released about 32 times as much.

1. Mineral, Virginia 2011 M 5.8 63,000× the energy of this one
2. Magna, Utah 2020 M 5.7 45,000× the energy of this one
3. Around the size people start to feel M 3.0 4× the energy of this one
4. This earthquake M 2.6 about 240 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 250,000 times the energy of this one.

Before 2016, the USGS record lists 94 earthquakes of M5 or more within 50 km; the five largest:

1. 7.2 162 km WSW of Adak, Alaska · 48 km SSW of this epicentre Mar 16, 1957
2. 6.6 152 km WSW of Adak, Alaska · 45 km S of this epicentre Mar 13, 1957
3. 6.6 174 km W of Adak, Alaska · 36 km W of this epicentre Apr 16, 2008
4. 6.5 167 km WSW of Adak, Alaska · 42 km SSW of this epicentre Jan 27, 1943
5. 6.4 187 km W of Adak, Alaska · 49 km W of this epicentre Apr 15, 2008

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 51.8237, -178.6449. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 1.8 139 km W of Adak, Alaska 14:06 UTC
2. 1.5 140 km W of Adak, Alaska 10:16 UTC
3. 1.6 130 km WSW of Adak, Alaska 08:34 UTC
4. 1.8 135 km W of Adak, Alaska 16:21 UTC
5. 2.0 136 km WNW of Adak, Alaska 10:12 UTC
6. 2.5 166 km W of Adak, Alaska 20:33 UTC
7. 1.9 143 km W of Adak, Alaska 05:06 UTC
8. 2.7 132 km WSW of Adak, Alaska 23:05 UTC
9. 1.5 127 km WSW of Adak, Alaska 09:09 UTC
10. 1.6 148 km WSW of Adak, Alaska 22:13 UTC
11. 1.7 145 km WSW of Adak, Alaska 12:49 UTC
12. 2.0 107 km W of Adak, Alaska 06:01 UTC
13. 1.6 115 km WSW of Adak, Alaska 09:45 UTC
14. 2.8 157 km WSW of Adak, Alaska 00:53 UTC
15. 3.7 157 km WSW of Adak, Alaska 18:38 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 08:54 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.