Earthquake near Dutch Harbor, AK

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 21 km (13 mi) from the epicentre. In Dutch Harbor, 18 km away, the estimate is intensity II (weak). 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.

Likely felt in: Unalaska 19 km, intensity II. Estimated for each town centre; each link is that town's own record.

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 4.6 on 2018-11-15 — about 1,400 times the energy of this one.

Before 2016, the USGS record lists 13 earthquakes of M5 or more within 50 km; the five largest:

1. 6.0 51 km SW of Unalaska, Alaska · 38 km SW of this epicentre Jul 19, 1986
2. 6.0 64 km SW of Unalaska, Alaska · 50 km SW of this epicentre Jul 19, 1986
3. 5.9 27 km WNW of Dutch Harbor, Alaska · 15 km NNW of this epicentre Apr 21, 1972
4. 5.9 13 km NE of Dutch Harbor, Alaska · 30 km ENE of this epicentre Sep 1, 2006
5. 5.4 48 km WSW of Unalaska, Alaska · 31 km WSW of this epicentre Oct 19, 1991

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 53.8676, -166.8178. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.6 8 km SE of Unalaska, Alaska 06:09 UTC
2. 1.6 6 km NNW of Dutch Harbor, Alaska 02:51 UTC
3. 1.8 40 km SSW of Unalaska, Alaska 15:22 UTC
4. 2.9 10 km NE of Dutch Harbor, Alaska 19:51 UTC
5. 1.9 22 km SSE of Unalaska, Alaska 10:58 UTC
6. 1.6 53 km SW of Unalaska, Alaska 14:34 UTC
7. 2.5 43 km S of Unalaska, Alaska 09:53 UTC
8. 2.1 48 km SSW of Unalaska, AK 11:50 UTC
9. 1.7 50 km SW of Unalaska, Alaska 05:14 UTC
10. 1.6 58 km SW of Unalaska, Alaska 09:53 UTC
11. 2.3 Fox Islands, Aleutian Islands, Alaska 04:37 UTC
12. 1.6 38 km S of Unalaska, Alaska 14:36 UTC
13. 1.8 27 km WSW of Unalaska, Alaska 00:19 UTC
14. 2.6 58 km SW of Unalaska, Alaska 02:18 UTC
15. 2.1 37 km W of Dutch Harbor, Alaska 08:41 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 08:23 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.