M4.1 Earthquake south of Alaska — December 6, 2021
2021-12-06 22:20:49 UTC (2021-12-06) · approx. 12:20 PM UTC-10 local
On December 6, 2021 at 22:20 UTC, a magnitude 4.1 shallow crustal earthquake struck south of Alaska, at a depth of 28.4 km and coordinates 55.6849°, -155.9644°.
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
Population exposure (USGS PAGER)
Estimated population that experienced each level of shaking. Based on the USGS PAGER rapid impact assessment, which combines ShakeMap output with global population grids.
| Shaking intensity (MMI) | Description | Population exposed |
|---|
Earthquake Details
-155.9644°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 4.1 earthquake south of Alaska?
The magnitude 4.1 earthquake that struck south of Alaska on December 6, 2021 at 22:20 UTC had a depth of 28.4 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: ak021fmnxxcp). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, December 6, 2021). M4.1 Earthquake south of Alaska — December 6, 2021. Retrieved February 12, 2022 from https://www.earthquaketracker.org/earthquakes/event/ak021fmnxxcp/