Mag. 4.0 earthquake - Gulf of Alaska, 63 mi southeast of Sand Point, Alaska, USA, on 20 Oct 1:33 pm (GMT -11) -
This quake was likely an aftershock of the 7.6 quake Gulf of Alaska, 60 mi southeast of Sand Point, Aleutians East County, Alaska, USA, 19 Oct 2020 11:54 am (GMT -9), which had occurred 1 day 4 hours earlier.
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Light magnitude 4.0 earthquake at 24 km depth
21 Oct 01:01 UTC: First to report: USGS after 27 minutes.
21 Oct 02:20: Magnitude recalculated from 3.7 to 4.0. Hypocenter depth recalculated from 16.5 to 23.6 km (from 10.3 to 14.7 mi). Epicenter location corrected by 16.1 km (10 mi) towards NNW.
21 Oct 02:20: Magnitude recalculated from 3.7 to 4.0. Hypocenter depth recalculated from 16.5 to 23.6 km (from 10.3 to 14.7 mi). Epicenter location corrected by 16.1 km (10 mi) towards NNW.
Local time at epicenter: 20 Oct 1:33 pm (GMT -11)
Magnitude: 4
Depth: 23.6 km
Epicenter latitude / longitude: 54.5676°N / 159.6697°W
(Gulf of Alaska, Alaska, United States)Nearest volcano: Stepovak Bay 2 (167 km / 104 mi)
Nearby towns and cities:
101 km (63 mi) SSE of Sand Point (pop: 1,060) --> See nearby quakes!
153 km (95 mi) SSW of Perryville (pop: 113) --> See nearby quakes!
178 km (111 mi) ESE of King Cove (pop: 1,010) --> See nearby quakes!
196 km (122 mi) SSW of Chignik Lake (pop: 73) --> See nearby quakes!
207 km (129 mi) ESE of Cold Bay (pop: 123) --> See nearby quakes!
399 km (248 mi) E of Akutan (pop: 1,040) --> See nearby quakes!
453 km (281 mi) ENE of Unalaska (pop: 4,490) --> See nearby quakes!
574 km (357 mi) SW of Kodiak (pop: 6,250) --> See nearby quakes!
6149 km (3821 mi) NW of Washington DC (District of Columbia) (pop: 601,700) --> See nearby quakes!
6149 km (3821 mi) NW of Washington DC (District of Columbia) (pop: 601,700) --> See nearby quakes!
25 km (16 mi) SSW of Chernabura Island --> See nearby quakes!
Weather at epicenter at time of quake:
Overcast Clouds
7.7°C (46 F), humidity: 66%, wind: 5 m/s (9 kts) from E
Primary data source: USGS (United States Geological Survey)
Overcast Clouds
7.7°C (46 F), humidity: 66%, wind: 5 m/s (9 kts) from EEstimated released energy: 6.3 x 1010 joules (17.5 megawatt hours, equivalent to 15.1 tons of TNT) More info
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.
| Magnitude | Depth | Location | Source |
| M 4.0 | 24 km | 100 Km SSE of Sand Point, Alaska, USA | USGS |
| M 4.0 | 24 km | South Of Alaska, USA | EMSC |
User reports for this quake
User reports estimate the perceived ground shaking intensity according to the MMI (Modified Mercalli Intensity) scale.
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Earlier earthquakes in the same area
Mag. 4.0 earthquake - Gulf of Alaska, 63 mi southeast of Sand Point, Alaska, USA, on 20 Oct 1:33 pm (GMT -11)
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