M3.8 Earthquake 84 km NE of Adak, Alaska — October 9, 2021
2021-10-09 23:07:50 UTC (2021-10-09) · approx. 11:07 AM UTC-12 local
On October 9, 2021 at 23:07 UTC, a magnitude 3.8 intermediate depth earthquake struck 84 km NE of Adak, Alaska, at a depth of 182.5 km and coordinates 52.4044°, -175.7518°.
Physical scale: An earthquake of magnitude 3.8 releases seismic energy equivalent to roughly 7.6 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 252 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
-175.7518°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 3.8 earthquake near Adak, Alaska?
The magnitude 3.8 earthquake that struck 84 km NE of Adak, Alaska on October 9, 2021 at 23:07 UTC had a depth of 182.5 km. For context, this was a minor earthquake typically detected only by instruments.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 3.8 earthquakes can continue for several days and gradually diminish over time.
Actions
Understanding This Data
Magnitude 3.8 earthquakes are typically only recorded by instruments.
Authoritative source: USGS event page (event ID: us6000fuk6). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, October 9, 2021). M3.8 Earthquake 84 km NE of Adak, Alaska — October 9, 2021. Retrieved December 18, 2021 from https://www.earthquaketracker.org/earthquakes/event/us6000fuk6/