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Strong mag. 5.1 earthquake - North Pacific Ocean, 126 mi east of Unalaska, Aleutians West, Alaska, USA, on Thursday, Sep 9, 2021 at 8:23 am (GMT -11) -

This quake was likely an aftershock of the 8.2 quake Chignik Earthquake, Gulf of Alaska, July 29, 2021 06:15 GMT, which had occurred 6 weeks earlier.
Strong mag. 5.1 earthquake - North Pacific Ocean, 126 mi east of Unalaska, Aleutians West, Alaska, USA, on Thursday, Sep 9, 2021 at 8:23 am (GMT -11) Strong mag. 5.1 earthquake - North Pacific Ocean, 126 mi east of Unalaska, Aleutians West, Alaska, USA, on Thursday, Sep 9, 2021 at 8:23 am (GMT -11)

Strong magnitude 5.1 earthquake at 22 km depth

9 Sep 19:33 UTC: First to report: GFZ after 10 minutes.
9 Sep 19:38: Now using data updates from USGS
9 Sep 19:47: Magnitude recalculated from 4.9 to 5.1. Hypocenter depth recalculated from 20.2 to 21.5 km (from 12.6 to 13.4 mi). Epicenter location corrected by 7.6 km (4.7 mi) towards SSE.

Earthquake details

Date & timeSep 9, 2021 19:23:25 UTC -
Local time at epicenterThursday, Sep 9, 2021 at 8:23 am (GMT -11)
Depth21.5 km
Epicenter latitude / longitude53.4726°N / 163.5308°W (North Pacific Ocean, Alaska, United States)
Antipode53.473°S / 16.469°E
Shaking intensityModerate shaking near epicenter
Felt0 reports
Primary data sourceUSGS (United States Geological Survey)
Nearest volcanoWestdahl (130 km / 81 mi)
Nearby towns and cities154 km (96 mi) S of False Pass (pop: 40) | Show on map | Quakes nearby
165 km (102 mi) ESE of Akutan (pop: 1,040) | Show on map | Quakes nearby
193 km (120 mi) SSW of King Cove (pop: 1,010) | Show on map | Quakes nearby
198 km (123 mi) SSW of Cold Bay (pop: 123) | Show on map | Quakes nearby
203 km (126 mi) E of Unalaska (pop: 4,490) | Show on map | Quakes nearby
204 km (127 mi) E of Dutch Harbor (pop: 4,380) | Show on map | Quakes nearby
285 km (177 mi) SW of Sand Point (pop: 1,060) | Show on map | Quakes nearby
318 km (198 mi) SSW of Nelson Lagoon (pop: 52) | Show on map | Quakes nearby
391 km (243 mi) SW of Perryville (pop: 113) | Show on map | Quakes nearby
435 km (270 mi) SW of Chignik Lake (pop: 73) | Show on map | Quakes nearby
Weather at epicenter at time of quakeClear Sky 11.7°C (53 F), humidity: 87%, wind: 10 m/s (19 kts) from WNW
Estimated seismic energy released2.8 x 1012 joules (783 megawatt hours, equivalent to 674 tons of TNT) | about seismic energy
Show interactive Map
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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.
5.122 kmUnimak Island Region, AlaskaUSGS
5.029 kmUnimak Island Region, AlaskaGFZ
5.119 kmUnimak Island Region, AlaskaGeoAu
4.930 kmUnimak Island Region, AlaskaBMKG


Seismic station: Adak, Aleutian Islands, Alaska (ADK/IU network) | Distance from quake: 903 km / 561 mi | Show on map | Station Info
Seismic station Adak, Aleutian Islands, 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. Source: IRIS Buffer of Uniform Data (BUD) webtool
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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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