131 km WSW of Adak, Alaska

2016-04-23 23:02 UTC · 8.0 km deep · released about 43 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: 2016-04-23 23:02 UTC
Magnitude: M 4.3 (mb)
Depth: 8.0 km below the surface
Felt: no reports yet
Measured shaking: intensity III (ShakeMap)
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 43 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.3 would have released about 32 times as much.

Northridge, California 1994 M 6.7 4,000× the energy of this one
Mineral, Virginia 2011 M 5.8 180× the energy of this one
Magna, Utah 2020 M 5.7 130× the energy of this one
This earthquake M 4.3 about 43 tons of TNT
Around the size people start to feel M 3.0 this one released 89× 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 51.6367, -178.4986. Map © OpenStreetMap contributors.

Aftershocks so far

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

2.6 128 km WSW of Adak, Alaska 03:03 UTC
1.8 137 km WSW of Adak, Alaska 08:38 UTC
1.6 130 km W of Adak, Alaska 06:09 UTC
2.9 100 km WSW of Adak, Alaska 21:54 UTC
2.0 130 km W of Adak, Alaska 03:28 UTC
2.8 132 km W of Adak, Alaska 12:54 UTC
1.8 154 km WSW of Adak, Alaska 08:42 UTC
1.6 130 km WSW of Adak, Alaska 23:18 UTC
1.7 113 km WSW of Adak, Alaska 12:24 UTC
1.5 116 km WSW of Adak, Alaska 00:31 UTC
1.5 131 km WSW of Adak, Alaska 16:28 UTC
1.7 126 km WSW of Adak, Alaska 14:23 UTC
3.1 136 km W of Adak, Alaska 05:26 UTC
2.0 129 km WSW of Adak, Alaska 22:15 UTC
2.1 125 km WSW of Adak, Alaska 14:44 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 02:44 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.