171 km SW of Nikolski, Alaska

Yes. A magnitude 4.7 earthquake was recorded 171 km SW of Nikolski, Alaska at 08:47 UTC on 2017-06-25, 37 km deep.

2017-06-25 08:47 UTC · 37 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: 2017-06-25 08:47 UTC
Magnitude: M 4.7 (mb)
Depth: 37 km below the surface
Felt: no reports yet
Status: Reviewed by a seismologist

USGS · last changed by USGS 1194 days ago · we first saw it 1194 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 155 km (96 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 5.2 on 2017-05-19 — about 5.6 times the energy of this one.

Before 2016, the USGS record lists 63 earthquakes of M5 or more within 50 km; the five largest:

6.6 135 km SW of Nikolski, Alaska · 45 km ENE of this epicentre Dec 23, 1906
6.2 179 km SW of Nikolski, Alaska · 13 km S of this epicentre Jun 4, 1956
6.2 Fox Islands, Aleutian Islands, Alaska · 29 km S of this epicentre Mar 10, 1957
6.1 207 km ESE of Atka, Alaska · 48 km WSW of this epicentre Mar 13, 1957
6.1 Fox Islands, Aleutian Islands, Alaska · 13 km SW of this epicentre Jan 11, 1961

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.

2.4 179 km WSW of Nikolski, Alaska 20:09 UTC
2.5 187 km SW of Nikolski, Alaska 19:05 UTC
3.4 133 km SW of Nikolski, Alaska 15:28 UTC
2.6 130 km SW of Nikolski, Alaska 09:34 UTC
3.1 128 km SW of Nikolski, Alaska 08:38 UTC
3.8 149 km SW of Nikolski, Alaska 21:03 UTC
3.4 138 km SW of Nikolski, Alaska 16:53 UTC
3.7 131 km WSW of Nikolski, Alaska 10:48 UTC
3.7 134 km SW of Nikolski, Alaska 04:10 UTC
3.9 178 km WSW of Nikolski, Alaska 09:31 UTC
2.7 131 km SW of Nikolski, Alaska 14:33 UTC
3.0 182 km SW of Nikolski, Alaska 19:39 UTC
3.7 170 km WSW of Nikolski, Alaska 00:10 UTC
3.4 130 km SW of Nikolski, Alaska 23:36 UTC
4.3 139 km SW of Nikolski, Alaska 02:22 UTC

Counted from the QuakeIndex database, which ingests the USGS feed every 30 seconds · as of 11:50 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.