250 km WSW of Adak, Alaska

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon.

At this magnitude and depth, people at rest would likely notice it out to about 170 km (106 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 240 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.8 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 710× the energy of this one
2. Mineral, Virginia 2011 M 5.8 32× the energy of this one
3. Magna, Utah 2020 M 5.7 22× the energy of this one
4. This earthquake M 4.8 about 240 tons of TNT
5. Around the size people start to feel M 3.0 this one released 500× more

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 6.1 on 2020-01-26 — about 89 times the energy of this one.

Before 2016, the USGS record lists 68 earthquakes of M5 or more within 50 km; the five largest:

1. 7.2 238 km WSW of Adak, Alaska · 25 km N of this epicentre Mar 22, 1905
2. 6.9 231 km WSW of Adak, Alaska · 42 km N of this epicentre May 14, 1969
3. 6.8 235 km WSW of Adak, Alaska · 39 km N of this epicentre May 6, 1987
4. 6.7 237 km WSW of Adak, Alaska · 48 km N of this epicentre Oct 13, 1926
5. 6.7 239 km WSW of Adak, Alaska · 43 km N of this epicentre Aug 2, 2007

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 50.9254, -179.9029. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.8 240 km WSW of Adak, Alaska 04:27 UTC
2. 2.2 237 km WSW of Adak, Alaska 02:37 UTC
3. 2.5 244 km WSW of Adak, Alaska 02:14 UTC
4. 2.8 244 km WSW of Adak, Alaska 00:48 UTC
5. 2.3 239 km WSW of Adak, Alaska 00:47 UTC
6. 3.4 242 km WSW of Adak, Alaska 00:34 UTC
7. 5.7 239 km WSW of Adak, Alaska 00:31 UTC
8. 2.7 244 km WSW of Adak, Alaska 02:54 UTC
9. 2.1 244 km WSW of Adak, Alaska 00:41 UTC
10. 1.9 239 km WSW of Adak, Alaska 03:11 UTC
11. 2.4 243 km WSW of Adak, Alaska 06:05 UTC
12. 4.0 244 km WSW of Adak, Alaska 17:39 UTC
13. 2.9 240 km WSW of Adak, Alaska 23:53 UTC
14. 3.2 Andreanof Islands, Aleutian Islands, Alaska 11:14 UTC
15. 2.2 214 km WSW of Adak, Alaska 01:20 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 08:42 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.