91 km SSE of Chignik, Alaska

Yes. A magnitude 4.2 earthquake was recorded 91 km SSE of Chignik, Alaska at 06:35 UTC on 2021-07-29, 7.3 km deep.

2021-07-29 06:35 UTC · 7.3 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: 2021-07-29 06:35 UTC
Magnitude: M 4.2 (ml)
Depth: 7.3 km below the surface
Felt: no reports yet
Status: Reviewed by a seismologist

USGS · last changed by USGS 1867 days ago · we first saw it 1867 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 112 km (70 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

The largest earthquake within 50 km since 2016 was M 8.2 on 2021-07-29 — about 1,000,000 times the energy of this one.

Before 2016, the USGS record lists 13 earthquakes of M5 or more within 50 km; the five largest:

8.2 1938 Semidi Islands, Alaska Earthquake · 45 km SSW of this epicentre Nov 10, 1938
6.9 105 km ESE of Perryville, Alaska · 16 km SSE of this epicentre Nov 17, 1938
6.7 121 km SE of Chignik, Alaska · 44 km ESE of this epicentre Feb 13, 1979
6.2 74 km SE of Perryville, Alaska · 40 km WSW of this epicentre Aug 6, 1927
6.0 98 km ESE of Perryville, Alaska · 12 km S of this epicentre Jan 2, 1985

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

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

2.1 123 km SE of Perryville, Alaska 14:32 UTC
2.1 122 km SE of Perryville, Alaska 13:58 UTC
3.9 135 km SSE of Chignik, Alaska 13:28 UTC
2.2 114 km SE of Chignik, Alaska 13:22 UTC
2.9 114 km SE of Chignik, Alaska 13:11 UTC
2.4 138 km SE of Perryville, Alaska 12:49 UTC
2.5 83 km SE of Perryville, Alaska 12:33 UTC
2.2 70 km SE of Perryville, Alaska 10:19 UTC
2.2 128 km SE of Perryville, Alaska 10:08 UTC
2.0 65 km SE of Perryville, Alaska 10:06 UTC
4.0 132 km SE of Perryville, Alaska 09:58 UTC
2.1 106 km SE of Perryville, Alaska 09:20 UTC
2.4 120 km SE of Perryville, Alaska 06:09 UTC
2.2 113 km SE of Perryville, Alaska 05:29 UTC
3.0 118 km SE of Perryville, Alaska 04:21 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 10:05 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.