Light mag. 3.9 earthquake - Bering Sea, 51 mi southwest of Atka, Aleutians West, Alaska, USA, on 18 Jul 11:30 am (GMT -9) -
Light magnitude 3.9 earthquake at 49 km depth
18 Jul 20:58 UTC: First to report: EMSC after 28 minutes.
18 Jul 20:58: Now using data updates from USGS
18 Jul 21:02: Magnitude recalculated from 3.5 to 3.9. Hypocenter depth recalculated from 25.9 to 48.9 km (from 16.1 to 30 mi). Epicenter location corrected by 22 km (14 mi) towards NNW.
18 Jul 20:58: Now using data updates from USGS
18 Jul 21:02: Magnitude recalculated from 3.5 to 3.9. Hypocenter depth recalculated from 25.9 to 48.9 km (from 16.1 to 30 mi). Epicenter location corrected by 22 km (14 mi) towards NNW.
Update Sun, 18 Jul 2021, 21:06
Small magnitude 3.9 earthquake 51 miles southwest of Atka, Alaska, United States3.9 quake 18 Jul 11:30 am (GMT -9)
Just 36 minutes ago, a 3.9-magnitude earthquake struck near Atka, Aleutians West, Alaska, USA. The tremor was recorded in the morning on Sunday 18 July 2021 at 11:30 am local time, at a moderately shallow depth of 30 miles below the surface.
The event was filed by the United States Geological Survey, the first seismological agency to report it.
Our monitoring service identified a second report from the European-Mediterranean Seismological Centre (EMSC) which listed the quake at magnitude 3.9 as well.
According to preliminary calculations, we do not expect that the quake was felt by many people and did not cause any damage. In Atka (pop. 64, 51 miles away), the quake was probably not felt.
The event was filed by the United States Geological Survey, the first seismological agency to report it.
Our monitoring service identified a second report from the European-Mediterranean Seismological Centre (EMSC) which listed the quake at magnitude 3.9 as well.
According to preliminary calculations, we do not expect that the quake was felt by many people and did not cause any damage. In Atka (pop. 64, 51 miles away), the quake was probably not felt.
Earthquake data
Earthquake details
| Date & time | Jul 18, 2021 20:30:13 UTC - |
| Local time at epicenter | 18 Jul 11:30 am (GMT -9) |
| Status | Confirmed |
| Magnitude | 3.9 |
| Depth | 48.9 km |
| Epicenter latitude / longitude | 51.7744°N / 175.1854°W  (Bering Sea, Alaska, United States) |
| Antipode | 51.774°S / 4.815°E |
| Shaking intensity | Weak shaking near epicenter |
| Felt | 0 reports |
| Primary data source | USGS (United States Geological Survey) |
| Nearest volcano | Kasatochi (49 km / 30 mi) |
| Nearby towns and cities | 82 km (51 mi) SW of Atka (pop: 64) | Show on map | Quakes nearby 100 km (62 mi) E of Adak (pop: 332) | Show on map | Quakes nearby |
| Weather at epicenter at time of quake | Overcast Clouds  8.5°C (47 F), humidity: 96%, wind: 9 m/s (17 kts) from SSW |
| Estimated seismic energy released | 4.5 x 1010 joules (12.4 megawatt hours, equivalent to 10.7 tons of TNT) | about seismic energy |
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.
| Mag. | Depth | Location | Source |
| 3.9 | 49 km | 82 Km SW of Atka, Alaska | USGS |
| 3.9 | 49 km | 90 Km SW of Atka, Alaska | EMSC |
User reports for this quake
User reports estimate the perceived ground shaking intensity according to the MMI (Modified Mercalli Intensity) scale.
Earlier earthquakes in the same area
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