99 km S of Unalaska, Alaska

Yes. A magnitude 2.1 earthquake was recorded 99 km S of Unalaska, Alaska, at 9:17 pm AKDT on 5 August 2016 (05:17 UTC), 16 km deep.

2016-08-06 05:17 UTC · 16 km deep · released about 43 lb of TNT

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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: 2016-08-06 05:17 UTC
Magnitude: M 2.1 (ml)
Depth: 16 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 minor earthquake. Quakes this small are rarely felt and do not cause damage.

At this magnitude and depth, people at rest would likely notice it out to about 6 km (4 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 lb of TNT. Magnitude is logarithmic: each whole step up releases about 32 times more energy, so a magnitude 3.1 would have released about 32 times as much.

Mineral, Virginia 2011 M 5.8 350,000× the energy of this one
Magna, Utah 2020 M 5.7 250,000× the energy of this one
Around the size people start to feel M 3.0 22× the energy of this one
This earthquake M 2.1 about 43 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 5.4 on 2016-07-26 — about 89,000 times the energy of this one.

Before 2016, the USGS record lists 20 earthquakes of M5 or more within 50 km; the five largest:

6.2 130 km S of Unalaska, Alaska · 46 km SW of this epicentre Jan 21, 1952
6.2 74 km SSW of Unalaska, Alaska · 49 km NW of this epicentre Oct 31, 1985
6.1 90 km SE of Unalaska, Alaska · 49 km ENE of this epicentre Jan 25, 1982
5.9 65 km SSE of Unalaska, Alaska · 38 km NNE of this epicentre Apr 21, 1941
5.8 81 km SSW of Unalaska, Alaska · 44 km WNW of this epicentre Jun 8, 1958

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

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Aftershocks so far

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

2.2 125 km S of Unalaska, Alaska 18:05 UTC
2.1 113 km S of Unalaska, Alaska 22:56 UTC
2.5 138 km S of Unalaska, Alaska 10:05 UTC
2.9 79 km S of Unalaska, Alaska 04:45 UTC
2.9 129 km S of Unalaska, Alaska 04:59 UTC
3.0 122 km S of Unalaska, Alaska 09:39 UTC
2.1 71 km S of Unalaska, Alaska 05:43 UTC
2.1 81 km S of Unalaska, Alaska 14:05 UTC
2.1 80 km S of Unalaska, Alaska 02:48 UTC
2.6 133 km S of Unalaska, Alaska 13:28 UTC
3.6 81 km SSW of Unalaska, Alaska 06:27 UTC
2.6 85 km SSW of Unalaska, Alaska 06:24 UTC
1.9 55 km S of Unalaska, Alaska 16:40 UTC
1.9 Fox Islands, Aleutian Islands, Alaska 02:51 UTC
2.2 75 km SSW of Unalaska, Alaska 03:29 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 08:13 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.