158 km SE of Chignik, Alaska

Yes. A magnitude 2.4 earthquake was recorded 158 km SE of Chignik, Alaska at 20:35 UTC on 2021-07-31, 47 km deep.

2021-07-31 20:35 UTC · 47 km deep · released about 120 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: 2021-07-31 20:35 UTC
Magnitude: M 2.4 (ml)
Depth: 47 km below the surface
Felt: no reports yet
Status: Reviewed by a seismologist

USGS · last changed by USGS 1925 days ago · we first saw it 1925 days ago

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

At this magnitude and depth it was probably too small to be felt, even directly above it. 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 120 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.4 would have released about 32 times as much.

Mineral, Virginia 2011 M 5.8 130,000× the energy of this one
Magna, Utah 2020 M 5.7 89,000× the energy of this one
Around the size people start to feel M 3.0 7.9× the energy of this one
This earthquake M 2.4 about 120 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.

For this area

The largest earthquake within 50 km since 2016 was M 5.5 on 2021-07-30 — about 45,000 times the energy of this one.

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

7.0 164 km SE of Chignik, Alaska · 7 km SSE of this epicentre Sep 4, 1989
6.9 143 km ESE of Chignik, Alaska · 48 km NNE of this epicentre Feb 13, 1951
6.7 121 km SE of Chignik, Alaska · 45 km W of this epicentre Feb 13, 1979
6.6 128 km SE of Chignik, Alaska · 31 km NNW of this epicentre Jul 28, 1934
6.2 189 km SE of Chignik, Alaska · 48 km S of this epicentre Mar 18, 1945

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.

2.4 129 km SE of Chignik, Alaska 05:46 UTC
2.8 139 km SE of Chignik, Alaska 03:22 UTC
2.3 159 km SE of Chignik, Alaska 15:30 UTC
2.6 158 km SE of Chignik, Alaska 12:45 UTC
2.5 191 km SE of Chignik, Alaska 10:20 UTC
2.5 190 km SE of Chignik, Alaska 08:53 UTC
3.7 156 km SE of Chignik, Alaska 06:04 UTC
2.7 202 km SE of Chignik, Alaska 06:18 UTC
3.6 194 km SE of Chignik, Alaska 06:08 UTC
4.0 160 km SE of Chignik, Alaska 20:41 UTC
2.4 146 km SE of Chignik, Alaska 11:31 UTC
2.4 113 km SE of Chignik, Alaska 05:40 UTC
2.6 150 km SE of Chignik, Alaska 00:39 UTC
2.2 south of Alaska 23:01 UTC
2.5 160 km SE of Chignik, Alaska 22:22 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 10:38 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.