south of Alaska

Yes. A magnitude 4.7 earthquake was recorded south of Alaska at 05:23 UTC on 2023-09-12, 4.7 km deep.

2023-09-12 05:23 UTC · 4.7 km deep · released about 170 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: 2023-09-12 05:23 UTC
Magnitude: M 4.7 (mb)
Depth: 4.7 km below the surface
Felt: no reports yet
Measured shaking: intensity II (ShakeMap)
Status: Reviewed by a seismologist

USGS · last changed by USGS 1091 days ago · we first saw it 1091 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 159 km (99 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 170 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.7 would have released about 32 times as much.

Northridge, California 1994 M 6.7 1,000× the energy of this one
Mineral, Virginia 2011 M 5.8 45× the energy of this one
Magna, Utah 2020 M 5.7 32× the energy of this one
This earthquake M 4.7 about 170 tons of TNT
Around the size people start to feel M 3.0 this one released 350× 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 since 2016 was M 5.6 on 2021-09-16 — about 22 times the energy of this one.

Before 2016, the USGS record lists 10 earthquakes of M5 or more within 50 km; the five largest:

7.0 164 km SE of Chignik, Alaska · 38 km N of this epicentre Sep 4, 1989
6.2 189 km SE of Chignik, Alaska · 11 km WSW of this epicentre Mar 18, 1945
6.1 210 km SE of Chignik, Alaska · 48 km ENE of this epicentre Nov 15, 1955
6.0 168 km SE of Chignik, Alaska · 30 km N of this epicentre Nov 16, 1938
5.6 171 km SE of Chignik, Alaska · 22 km NW of this epicentre Jun 22, 1970

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

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

3.2 199 km SE of Perryville, Alaska 16:48 UTC
4.5 201 km SE of Perryville, Alaska 14:33 UTC
2.4 175 km SE of Chignik, Alaska 23:24 UTC
2.6 199 km SE of Perryville, Alaska 19:43 UTC
3.1 202 km SE of Perryville, Alaska 06:08 UTC
2.8 216 km SE of Perryville, Alaska 21:46 UTC
2.3 215 km SE of Chignik, Alaska 11:11 UTC
3.0 148 km SE of Chignik, Alaska 00:05 UTC
2.6 200 km SE of Chignik, Alaska 18:19 UTC
2.7 202 km SE of Chignik, Alaska 18:16 UTC
3.5 205 km SE of Chignik, Alaska 10:01 UTC
2.8 198 km SE of Perryville, Alaska 21:03 UTC
2.0 175 km SE of Chignik, Alaska 13:41 UTC
2.4 209 km SE of Chignik, Alaska 03:04 UTC
2.6 202 km SE of Perryville, Alaska 11:20 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 13:57 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.