M3.3 Earthquake 49 km N of Atka, Alaska — August 21, 2021
2021-08-21 21:45:53 UTC (2021-08-21) · approx. 9:45 AM UTC-12 local
On August 21, 2021 at 21:45 UTC, a magnitude 3.3 intermediate depth earthquake struck 49 km N of Atka, Alaska, at a depth of 247.2 km and coordinates 52.6413°, -174.1141°.
Physical scale: An earthquake of magnitude 3.3 releases seismic energy equivalent to roughly 1.3 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 114 m — a useful intuition for the size of the slip patch on the fault.
Earthquake Details
-174.1141°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 3.3 earthquake near Atka, Alaska?
The magnitude 3.3 earthquake that struck 49 km N of Atka, Alaska on August 21, 2021 at 21:45 UTC had a depth of 247.2 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 3.3 earthquakes can continue for several days and gradually diminish over time.
Actions
Understanding This Data
Magnitude 3.3 earthquakes are typically only recorded by instruments.
Authoritative source: USGS event page (event ID: us7000f6hj). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, August 21, 2021). M3.3 Earthquake 49 km N of Atka, Alaska — August 21, 2021. Retrieved November 2, 2021 from https://www.earthquaketracker.org/earthquakes/event/us7000f6hj/