153 km SSE of Old Harbor, 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 40 km (25 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 1,300 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.1 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 250,000× the energy of this one
2. Mineral, Virginia 2011 M 5.8 11,000× the energy of this one
3. Magna, Utah 2020 M 5.7 7,900× the energy of this one
4. This earthquake M 3.1 about 1,300 lb of TNT
5. Around the size people start to feel M 3.0 this one released 1.4× 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 4.7 on 2019-12-21 — about 250 times the energy of this one.

Before 2016, the USGS record lists 16 earthquakes of M5 or more within 50 km; the five largest:

1. 6.2 129 km SSE of Old Harbor, Alaska · 24 km NNW of this epicentre May 7, 1999
2. 5.9 114 km SE of Old Harbor, Alaska · 47 km N of this epicentre Mar 28, 1964
3. 5.9 124 km SSE of Old Harbor, Alaska · 29 km NNW of this epicentre Mar 30, 2009
4. 5.9 136 km SE of Old Harbor, Alaska · 30 km NNE of this epicentre May 16, 2009
5. 5.8 193 km SSE of Old Harbor, Alaska · 40 km SSE of this epicentre Apr 7, 1964

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 55.9788, -152.1495. Map © OpenStreetMap contributors.

Aftershocks so far

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

1. 2.5 167 km SSE of Old Harbor, Alaska 15:29 UTC
2. 2.4 153 km SSE of Old Harbor, Alaska 16:18 UTC
3. 3.1 108 km SSE of Old Harbor, Alaska 03:23 UTC
4. 3.0 188 km SSE of Old Harbor, Alaska 00:48 UTC
5. 3.2 115 km SSE of Old Harbor, Alaska 00:06 UTC
6. 2.5 194 km SSE of Old Harbor, Alaska 07:52 UTC
7. 2.5 168 km SSE of Old Harbor, Alaska 21:22 UTC
8. 3.1 150 km SE of Old Harbor, Alaska 04:03 UTC
9. 3.2 142 km SE of Old Harbor, Alaska 07:52 UTC
10. 3.0 120 km SE of Old Harbor, Alaska 07:42 UTC
11. 4.6 117 km SE of Old Harbor, Alaska 06:35 UTC
12. 3.3 130 km SSE of Old Harbor, Alaska 08:27 UTC
13. 3.5 116 km SSE of Old Harbor, Alaska 12:52 UTC
14. 3.5 116 km SSE of Old Harbor, Alaska 11:59 UTC
15. 2.2 109 km SE of Old Harbor, Alaska 10:36 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 00:32 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.