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Light mag. 3.8 earthquake - North Pacific Ocean, 109 mi southwest of Unalaska, Aleutians West, Alaska, USA, on Tuesday, Dec 21, 2021 at 5:59 am (GMT -11) -

Light mag. 3.8 earthquake - North Pacific Ocean, 109 mi southwest of Unalaska, Aleutians West, Alaska, USA, on Tuesday, Dec 21, 2021 at 5:59 am (GMT -11) Light mag. 3.8 earthquake - North Pacific Ocean, 109 mi southwest of Unalaska, Aleutians West, Alaska, USA, on Tuesday, Dec 21, 2021 at 5:59 am (GMT -11)

Light magnitude 3.8 earthquake at 35 km depth

21 Dec 17:23 UTC: First to report: USGS after 24 minutes.
21 Dec 18:08: Magnitude recalculated from 3.7 to 3.8. Hypocenter depth recalculated from 40.1 to 35.0 km (from 25 to 22 mi). Epicenter location corrected by 3.8 km (2.3 mi) towards SSW.
Update Tue, 21 Dec 2021, 17:27

Small magnitude 3.7 quake hits 35 miles southeast of Nikolski, Alaska, United States early morning

3.7 quake 21 Dec 5:59 am (GMT -11)
3.7 quake 21 Dec 5:59 am (GMT -11)
A magnitude 3.7 earthquake near Nikolski, Aleutians West, Alaska, USA, was reported only 27 minutes ago by the United States Geological Survey, considered the key international and national agency that monitors seismic activity in the US. The earthquake occurred at a moderately shallow depth of 25 miles beneath the epicenter early morning on Tuesday, December 21st, 2021, at 5:59 am local time. The exact magnitude, epicenter, and depth of the quake might be revised within the next few hours or minutes as seismologists review data and refine their calculations, or as other agencies issue their report.
A second report was later issued by the European-Mediterranean Seismological Centre (EMSC), which listed it as a magnitude 3.7 earthquake as well.
Towns or cities near the epicenter where the quake might have been felt as very weak shaking include Nikolski (pop. 18) located 35 miles from the epicenter.

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Earthquake details

Date & timeDec 21, 2021 16:59:50 UTC -
Local time at epicenterTuesday, Dec 21, 2021 at 5:59 am (GMT -11)
Depth35.0 km
Epicenter latitude / longitude52.6313°N / 168.1716°W (North Pacific Ocean, Alaska, United States)
Antipode52.631°S / 11.828°E
Shaking intensityWeak shaking near epicenter
Felt0 reports
Primary data sourceUSGS (United States Geological Survey)
Nearest volcanoRecheschnoi (63 km / 39 mi)
Nearby towns and cities58 km (36 mi) SE of Nikolski (pop: 18) | Show on map | Quakes nearby
176 km (109 mi) SW of Unalaska (pop: 4,490) | Show on map | Quakes nearby
177 km (110 mi) SW of Dutch Harbor (pop: 4,380) | Show on map | Quakes nearby
231 km (143 mi) SW of Akutan (pop: 1,040) | Show on map | Quakes nearby
Weather at epicenter at time of quakeOvercast Clouds 6.1°C (43 F), humidity: 97%, wind: 9 m/s (18 kts) from S
Estimated seismic energy released3.2 x 1010 joules (8.78 megawatt hours, equivalent to 7.56 tons of TNT) | about seismic energy
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Data for the same earthquake reported by different agencies

Info: The more agencies report about the same quake and post similar data, the more confidence you can have in the data. It takes normally up to a few hours until earthquake parameters are calculated with near-optimum precision.
3.835 km57 Km SE of Nikolski, AlaskaUSGS
3.835 kmFox Islands, Aleutian IslandsRaspberryShake


Seismic station: Mount Tulik, Okmok Caldera, Alaska (OKTU/AV network) | Distance from quake: 84 km / 52 mi | Show on map | Station Info
Seismic station Mount Tulik, Okmok Caldera, Alaska: vertical movement plot around time of quake (source: IRIS/BUD)
Seismogram (vertical component) around time of quake. Thin dotted red line indicates time of quake. Seismic waves arrive some time later, depending on distance. Bandpass filter applied: 0.5-10.0 Hz. Source: IRIS Buffer of Uniform Data (BUD) webtool
Show more

User reports for this quake

User reports estimate the perceived ground shaking intensity according to the MMI (Modified Mercalli Intensity) scale.
There are no user reports for this quake.

Earlier earthquakes in the same area

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