187 km S of Atka, Alaska

2018-08-16 20:50 UTC · 10 km deep · released about 1.3 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: 2018-08-16 20:50 UTC
Magnitude: M 3.3 (ml)
Depth: 10 km below the surface
Felt: no reports yet
Status: Reviewed by a seismologist

USGS · last changed by USGS 1138 days ago · we first saw it 1138 days ago

This was a small earthquake. Shaking like this is often felt indoors nearby and very rarely causes damage.

How big was it?

This earthquake released about 1.3 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 4.3 would have released about 32 times as much.

Northridge, California 1994 M 6.7 130,000× the energy of this one
Mineral, Virginia 2011 M 5.8 5,600× the energy of this one
Magna, Utah 2020 M 5.7 4,000× the energy of this one
This earthquake M 3.3 about 1.3 tons of TNT
Around the size people start to feel M 3.0 this one released 2.8× 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 50.5132, -174.2931. Map © OpenStreetMap contributors.

Aftershocks so far

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

2.0 198 km S of Atka, Alaska 11:48 UTC
2.1 164 km S of Atka, Alaska 11:58 UTC
2.7 211 km S of Atka, Alaska 22:20 UTC
2.1 150 km S of Atka, Alaska 17:06 UTC
2.3 145 km S of Atka, Alaska 02:32 UTC
2.7 142 km S of Atka, Alaska 13:51 UTC
2.3 139 km S of Atka, Alaska 05:37 UTC
2.8 199 km SSW of Atka, Alaska 09:34 UTC
2.4 181 km S of Atka, Alaska 18:26 UTC
2.1 182 km SSW of Atka, Alaska 17:33 UTC
2.5 161 km S of Atka, Alaska 23:15 UTC
2.1 164 km S of Atka, Alaska 13:20 UTC
2.1 178 km S of Atka, Alaska 04:32 UTC
2.7 188 km S of Atka, Alaska 13:08 UTC
2.1 178 km S of Atka, Alaska 15:16 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 23:15 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 4.1 on 2017-03-01 — it released about 16 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.