M4.1 Earthquake 157 km ESE of Attu Station, Alaska — August 22, 2021
2021-08-22 22:17:08 UTC (2021-08-22) · approx. 10:17 AM UTC+12 local
On August 22, 2021 at 22:17 UTC, a magnitude 4.1 shallow crustal earthquake struck 157 km ESE of Attu Station, Alaska, at a depth of 64.9 km and coordinates 52.0793°, 175.1260°.
Physical scale: An earthquake of magnitude 4.1 releases seismic energy equivalent to roughly 21 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 406 m — a useful intuition for the size of the slip patch on the fault.
ShakeMap — predicted shaking intensity
Modeled ground-motion intensity contoured on the Modified Mercalli scale (MMI). Computed by the USGS from the moment-tensor solution and regional ground-motion prediction equations.
Source: U.S. Geological Survey ShakeMap. View interactive ShakeMap on USGS
Earthquake Details
175.1260°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 4.1 earthquake near Attu Station, Alaska?
The magnitude 4.1 earthquake that struck 157 km ESE of Attu Station, Alaska on August 22, 2021 at 22:17 UTC had a depth of 64.9 km. For context, this was a light earthquake commonly felt near the epicenter.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 4.1 earthquakes can continue for several days and gradually diminish over time.
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Understanding This Data
Magnitude 4.1 earthquakes are often felt but rarely cause damage.
Authoritative source: USGS event page (event ID: us6000f9uq). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, August 22, 2021). M4.1 Earthquake 157 km ESE of Attu Station, Alaska — August 22, 2021. Retrieved November 2, 2021 from https://www.earthquaketracker.org/earthquakes/event/us6000f9uq/