177 km SSW of Adak, Alaska

Yes. A magnitude 4.3 earthquake was recorded 177 km SSW of Adak, Alaska at 17:44 UTC on 2018-03-11, 22 km deep.

2018-03-11 17:44 UTC · 22 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: 2018-03-11 17:44 UTC
Magnitude: M 4.3 (mb)
Depth: 22 km below the surface
Felt: no reports yet
Nearest mapped fault: Alaska-Aleutian subduction zone, 4 km from its surface trace — near is not the same as on
Status: Reviewed by a seismologist

USGS · last changed by USGS 1191 days ago · we first saw it 1191 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 119 km (74 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 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.

For this area

The largest earthquake within 50 km (31 mi) since our catalogue begins in 2016. The previous largest was M 4.2 on 2016-07-24.

Before 2016, the USGS record lists 16 earthquakes of M5 or more within 50 km; the five largest:

6.5 184 km SSW of Adak, Alaska · 8 km SW of this epicentre Aug 15, 2007
6.1 198 km S of Adak, Alaska · 50 km SE of this epicentre May 22, 1957
6.1 189 km S of Adak, Alaska · 37 km ESE of this epicentre Jul 3, 1960
6.0 161 km SSW of Adak, Alaska · 20 km NNW of this epicentre Jan 11, 1934
6.0 136 km S of Adak, Alaska · 48 km NE of this epicentre Mar 11, 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

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

4.0 Andreanof Isl., Aleutian Islands, Alaska 13:21 UTC
2.7 213 km SSW of Adak, Alaska 01:01 UTC
3.1 178 km SSW of Adak, Alaska 12:38 UTC
3.3 188 km SSW of Adak, Alaska 06:49 UTC
2.3 178 km S of Adak, Alaska 06:12 UTC
2.3 179 km SSW of Adak, Alaska 09:04 UTC
3.9 177 km SSW of Adak, Alaska 22:03 UTC
3.4 204 km SSW of Adak, Alaska 16:41 UTC
2.0 183 km S of Adak, Alaska 16:15 UTC
2.1 186 km SSW of Adak, Alaska 14:40 UTC
3.4 200 km SSW of Adak, Alaska 03:03 UTC
1.7 209 km S of Adak, Alaska 01:05 UTC
2.5 168 km SSW of Adak, Alaska 21:15 UTC
1.9 176 km SSW of Adak, Alaska 23:35 UTC
3.4 219 km SSW of Adak, Alaska 18:06 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 15:59 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.