88 km SSE of Atka, Alaska

Yes. A magnitude 4.0 earthquake was recorded 88 km SSE of Atka, Alaska at 00:16 UTC on 2016-08-04, 35 km deep.

2016-08-04 00:16 UTC · 35 km deep · released about 15 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: 2016-08-04 00:16 UTC
Magnitude: M 4.0 (mb)
Depth: 35 km below the surface
Felt: no reports yet
Status: Reviewed by a seismologist

USGS · last changed by USGS 1200 days ago · we first saw it 1200 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 90 km (56 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 15 tons of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 5.0 would have released about 32 times as much.

Northridge, California 1994 M 6.7 11,000× the energy of this one
Mineral, Virginia 2011 M 5.8 500× the energy of this one
Magna, Utah 2020 M 5.7 350× the energy of this one
This earthquake M 4.0 about 15 tons of TNT
Around the size people start to feel M 3.0 this one released 32× 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 6.3 on 2016-03-12 — about 2,800 times the energy of this one.

Before 2016, the USGS record lists 119 earthquakes of M5 or more within 50 km; the five largest:

6.6 62 km SSE of Atka, Alaska · 27 km NNW of this epicentre Mar 10, 1957
6.6 89 km S of Atka, Alaska · 40 km W of this epicentre Mar 10, 1957
6.5 79 km SSE of Atka, Alaska · 17 km NNE of this epicentre Mar 12, 1957
6.5 99 km SE of Atka, Alaska · 49 km ENE of this epicentre Nov 9, 2015
6.2 79 km SSE of Atka, Alaska · 19 km NE of this epicentre Mar 22, 1987

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

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

3.9 120 km SSE of Atka, Alaska 19:08 UTC
2.8 102 km SE of Atka, Alaska 12:46 UTC
2.7 113 km SE of Atka, Alaska 09:03 UTC
3.2 63 km SE of Atka, Alaska 16:33 UTC
2.1 67 km SSE of Atka, Alaska 18:39 UTC
2.7 111 km S of Atka, Alaska 08:11 UTC
1.8 43 km SSE of Atka, Alaska 10:00 UTC
3.0 56 km SSE of Atka, Alaska 21:49 UTC
2.4 66 km SSE of Atka, Alaska 19:44 UTC
3.5 97 km SE of Atka, Alaska 06:41 UTC
2.6 101 km SE of Atka, Alaska 05:50 UTC
2.5 103 km SE of Atka, Alaska 05:47 UTC
3.1 100 km SE of Atka, Alaska 05:03 UTC
3.2 104 km SE of Atka, Alaska 05:01 UTC
3.5 90 km SSE of Atka, Alaska 22:15 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 21:19 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.