252 km SW of Adak, Alaska

Yes. A magnitude 4.2 earthquake was recorded 252 km SW of Adak, Alaska at 20:08 UTC on 2017-06-23, 26 km deep.

2017-06-23 20:08 UTC · 26 km deep · released about 30 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: 2017-06-23 20:08 UTC
Magnitude: M 4.2 (mb)
Depth: 26 km below the surface
Felt: no reports yet
Nearest mapped fault: Alaska-Aleutian subduction zone, 23 km from its surface trace — near is not the same as on
Status: Reviewed by a seismologist

USGS · last changed by USGS 1194 days ago · we first saw it 1194 days ago

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

At this magnitude and depth, people at rest would likely notice it out to about 109 km (68 mi) from the epicentre. Estimated from magnitude, depth and distance with the intensity equation USGS Did You Feel It? uses; felt reports, where there are any, are the measurement.

How big was it?

This earthquake released about 30 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.2 would have released about 32 times as much.

Northridge, California 1994 M 6.7 5,600× the energy of this one
Mineral, Virginia 2011 M 5.8 250× the energy of this one
Magna, Utah 2020 M 5.7 180× the energy of this one
This earthquake M 4.2 about 30 tons of TNT
Around the size people start to feel M 3.0 this one released 63× 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.

For this area

Tied for the largest within 50 km (31 mi) since 2016, with M 4.2 on 2017-03-02.

Before 2016, the USGS record lists 7 earthquakes of M5 or more within 50 km; the five largest:

6.8 Andreanof Islands, Aleutian Islands, Alaska · 19 km ESE of this epicentre Jun 22, 1913
6.7 254 km SW of Adak, Alaska · 48 km NW of this epicentre Sep 14, 1905
6.0 207 km SW of Adak, Alaska · 46 km NE of this epicentre Feb 7, 1926
6.0 254 km SW of Adak, Alaska · 17 km SE of this epicentre Jul 8, 1929
6.0 257 km SW of Adak, Alaska · 7 km S of this epicentre Jul 3, 1957

Since 2016: the QuakeIndex catalogue (US, M1.5+), built from the USGS FDSN event service. Before 2016: USGS ComCat, M5+ from 1900. Distances are between epicentres. This is the record, not a forecast.

Where

Map loads when it scrolls into view

Aftershocks so far

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

3.8 249 km SSW of Adak, Alaska 18:35 UTC
2.7 245 km SW of Adak, Alaska 12:59 UTC
2.6 269 km SW of Adak, Alaska 04:45 UTC
2.1 242 km SW of Adak, Alaska 14:22 UTC
1.9 254 km SW of Adak, Alaska 12:53 UTC
2.9 262 km SW of Adak, Alaska 14:01 UTC
2.8 270 km SW of Adak, Alaska 13:18 UTC
3.4 267 km SW of Adak, Alaska 01:48 UTC
3.9 251 km SW of Adak, Alaska 17:52 UTC
2.8 275 km SW of Adak, Alaska 08:27 UTC
2.3 266 km SW of Adak, Alaska 06:45 UTC
2.1 284 km SW of Adak, Alaska 08:10 UTC
2.8 252 km SW of Adak, Alaska 23:31 UTC
2.9 245 km SW of Adak, Alaska 14:11 UTC
2.7 248 km SW of Adak, Alaska 06:56 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 16:41 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.