M3.9 Earthquake 74 km E of Atka, Alaska — April 7, 2021
2021-04-07 22:21:20 UTC (2021-04-07) · approx. 10:21 AM UTC-12 local
On April 7, 2021 at 22:21 UTC, a magnitude 3.9 shallow crustal earthquake struck 74 km E of Atka, Alaska, at a depth of 6.2 km and coordinates 52.2285°, -173.1179°.
Physical scale: An earthquake of magnitude 3.9 releases seismic energy equivalent to roughly 11 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 296 m — a useful intuition for the size of the slip patch on the fault.
Earthquake Details
-173.1179°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 3.9 earthquake near Atka, Alaska?
The magnitude 3.9 earthquake that struck 74 km E of Atka, Alaska on April 7, 2021 at 22:21 UTC had a depth of 6.2 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 3.9 earthquakes can continue for several days and gradually diminish over time.
Actions
Understanding This Data
Magnitude 3.9 earthquakes are typically only recorded by instruments.
Authoritative source: USGS event page (event ID: us7000dxm0). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, April 7, 2021). M3.9 Earthquake 74 km E of Atka, Alaska — April 7, 2021. Retrieved June 12, 2021 from https://www.earthquaketracker.org/earthquakes/event/us7000dxm0/