216 km W of Adak, Alaska

2016-12-23 20:21 UTC · 47 km deep · released about 85 lb 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: 2016-12-23 20:21 UTC
Magnitude: M 2.3 (ml)
Depth: 47 km below the surface
Felt: no reports yet
Status: Reviewed by a seismologist

USGS · last changed by USGS 1151 days ago · we first saw it 1151 days ago

This was a minor earthquake. Quakes this small are rarely felt and do not cause damage.

How big was it?

This earthquake released about 85 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.3 would have released about 32 times as much.

Mineral, Virginia 2011 M 5.8 180,000× the energy of this one
Magna, Utah 2020 M 5.7 130,000× the energy of this one
Around the size people start to feel M 3.0 11× the energy of this one
This earthquake M 2.3 about 85 lb of TNT

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 51.8620, -179.7724. Map © OpenStreetMap contributors.

Aftershocks so far

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

2.8 201 km W of Adak, Alaska 13:55 UTC
2.1 226 km WSW of Adak, Alaska 09:23 UTC
2.5 227 km W of Adak, Alaska 09:23 UTC
2.5 216 km W of Adak, Alaska 04:35 UTC
2.9 217 km W of Adak, Alaska 21:08 UTC
2.3 206 km W of Adak, Alaska 22:45 UTC
2.9 219 km W of Adak, Alaska 06:19 UTC
2.3 184 km W of Adak, Alaska 17:50 UTC
4.1 181 km W of Adak, Alaska 07:33 UTC
2.4 220 km W of Adak, Alaska 12:48 UTC
2.0 209 km W of Adak, Alaska 06:05 UTC
2.3 Andreanof Islands, Aleutian Islands, Alaska 12:21 UTC
2.3 212 km W of Adak, Alaska 19:57 UTC
2.4 223 km W of Adak, Alaska 12:36 UTC
2.1 223 km W of Adak, Alaska 04:57 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 06:34 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 5.2 on 2016-11-23 — it released about 22,000 times the energy of this one.

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.