65 km SE of Cantwell, 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 73 km (45 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 11 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.9 would have released about 32 times as much.

1. Northridge, California 1994 M 6.7 16,000× the energy of this one
2. Mineral, Virginia 2011 M 5.8 710× the energy of this one
3. Magna, Utah 2020 M 5.7 500× the energy of this one
4. This earthquake M 3.9 about 11 tons of TNT
5. Around the size people start to feel M 3.0 this one released 22× 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 5.5 on 2021-04-08 — about 250 times the energy of this one.

Before 2016, the USGS record lists 4 earthquakes of M5 or more within 50 km:

1. 5.6 44 km S of Cantwell, AK · 46 km W of this epicentre May 29, 1931
2. 5.4 38 km SSE of Cantwell, Alaska · 28 km WNW of this epicentre Mar 17, 1979
3. 5.3 49 km S of Cantwell, Alaska · 36 km W of this epicentre Dec 28, 1990
4. 5.0 70 km ENE of Chase, Alaska · 48 km SW of this epicentre Feb 5, 1974

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 62.9520, -148.0930. Map © OpenStreetMap contributors.

Nearby places

Places and coordinates from the US Census Bureau Gazetteer (2024). Distances are from the epicentre.

Aftershocks so far

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

1. 2.0 50 km SE of Cantwell, Alaska 20:43 UTC
2. 1.9 69 km ESE of Cantwell, Alaska 15:58 UTC
3. 2.0 52 km SSE of Cantwell, Alaska 12:26 UTC
4. 2.0 37 km ESE of Cantwell, Alaska 16:53 UTC
5. 2.1 36 km ESE of Cantwell, Alaska 13:29 UTC
6. 1.9 61 km SE of Cantwell, Alaska 07:55 UTC
7. 1.7 54 km SSE of Cantwell, Alaska 05:57 UTC
8. 1.7 67 km ESE of Cantwell, Alaska 06:03 UTC
9. 3.0 72 km SSE of Cantwell, Alaska 23:30 UTC
10. 2.0 57 km SSE of Cantwell, Alaska 12:36 UTC
11. 1.9 66 km SE of Cantwell, Alaska 14:16 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 18:10 UTC. QuakeIndex does not forecast aftershocks. When USGS issues an operational aftershock forecast it appears on the USGS event page.

Revisions

USGS refines a solution as more stations report. Every change we have seen is listed here.

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.