9 km NW of Harding-Birch Lakes, Alaska

2021-09-14 05:56 UTC · 3.9 km deep · released about 340 tons of TNT

Distance rings around the epicentre, with the nearest towns at their true direction and later quakes as coloured dots. Not a shaking map — see the USGS ShakeMap for that.

When: 2021-09-14 05:56 UTC
Magnitude: M 4.9 (ml)
Depth: 3.9 km below the surface
Felt: 1086 reports · strongest reported intensity V
Measured shaking: intensity VI (ShakeMap)
USGS impact alert: green
Nearest: Fairbanks North Star Borough, 28 km NNE
Status: Reviewed by a seismologist

USGS · last changed by USGS 1113 days ago · we first saw it 1113 days ago

This was a light earthquake. It is usually felt clearly nearby and can rattle windows and dishes, but damage is uncommon. 1086 people have reported feeling it to USGS.

How big was it?

This earthquake released about 340 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.9 would have released about 32 times as much.

Northridge, California 1994 M 6.7 500× the energy of this one
Mineral, Virginia 2011 M 5.8 22× the energy of this one
Magna, Utah 2020 M 5.7 16× the energy of this one
This earthquake M 4.9 about 340 tons of TNT
Around the size people start to feel M 3.0 this one released 710× 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.

Where

Map loads when it scrolls into view

Epicentre 64.4374, -146.7370. Map © OpenStreetMap contributors.

Nearby places

Place	Distance	Direction
Fairbanks North Star Borough, AK	28 km (18 mi)	SSW of here	earthquakes near Fairbanks North Star Borough

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

Aftershocks so far

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

1.5 Central Alaska 00:38 UTC
1.5 8 km NW of Harding-Birch Lakes, Alaska 05:44 UTC
2.0 36 km SSW of Harding-Birch Lakes, Alaska 13:32 UTC
1.5 Central Alaska 21:03 UTC
1.6 Central Alaska 08:02 UTC
2.0 3 km ESE of Two Rivers, Alaska 09:46 UTC
1.7 5 km SW of Salcha, Alaska 03:27 UTC
2.0 22 km SW of Salcha, Alaska 18:23 UTC
1.6 Central Alaska 13:04 UTC
2.2 12 km WSW of Harding-Birch Lakes, Alaska 18:40 UTC
2.0 17 km NE of Harding-Birch Lakes, Alaska 02:15 UTC
1.7 17 km ENE of Eielson Air Force Base, Alaska 20:06 UTC
1.6 Central Alaska 14:07 UTC
2.1 19 km WSW of Salcha, Alaska 00:22 UTC
1.6 17 km WSW of Salcha, Alaska 22:48 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 22:18 UTC. QuakeIndex does not forecast aftershocks. When USGS issues an operational aftershock forecast it appears on the USGS event page.

For this area

The largest earthquake within 50 km in our catalogue was M 4.8 on 2021-07-23.

From the QuakeIndex catalogue, built from the USGS FDSN event service.

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.