155 km S of Adak, Alaska

2016-09-03 10:05 UTC · 10 km deep · released about 21 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: 2016-09-03 10:05 UTC
Magnitude: M 4.1 (mb)
Depth: 10 km below the surface
Felt: no reports yet
Status: Reviewed by a seismologist

USGS · last changed by USGS 1153 days ago · we first saw it 1153 days ago

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

How big was it?

This earthquake released about 21 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.1 would have released about 32 times as much.

Northridge, California 1994 M 6.7 7,900× the energy of this one
Mineral, Virginia 2011 M 5.8 350× the energy of this one
Magna, Utah 2020 M 5.7 250× the energy of this one
This earthquake M 4.1 about 21 tons of TNT
Around the size people start to feel M 3.0 this one released 45× 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 50.4782, -176.8344. Map © OpenStreetMap contributors.

Aftershocks so far

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

2.8 182 km S of Adak, Alaska 23:24 UTC
1.7 153 km S of Adak, Alaska 03:11 UTC
4.3 179 km S of Adak, Alaska 01:42 UTC
2.0 166 km S of Adak, Alaska 22:18 UTC
2.6 168 km S of Adak, Alaska 02:48 UTC
2.8 170 km S of Adak, Alaska 15:24 UTC
4.1 174 km S of Adak, Alaska 22:08 UTC
3.8 158 km S of Adak, Alaska 06:35 UTC
3.0 144 km S of Adak, Alaska 01:46 UTC
2.6 197 km S of Adak, Alaska 21:34 UTC
2.6 182 km S of Adak, Alaska 12:05 UTC
2.3 149 km S of Adak, Alaska 17:25 UTC
3.1 180 km S of Adak, Alaska 05:28 UTC
2.2 187 km S of Adak, Alaska 21:02 UTC
2.1 169 km SSW of Adak, Alaska 10:55 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 07:32 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.