M3.2 Earthquake 1 km NNE of Point MacKenzie, Alaska — September 24, 2021
2021-09-24 20:34:51 UTC (2021-09-24) · approx. 10:34 AM UTC-10 local
Felt by 18 people across nearby locations.
On September 24, 2021 at 20:34 UTC, a magnitude 3.2 shallow crustal earthquake struck 1 km NNE of Point MacKenzie, Alaska, at a depth of 43.3 km and coordinates 61.3736°, -149.9623°. The earthquake was reported felt by 18 peopleacross nearby locations, with a maximum shaking intensity of Modified Mercalli Intensity (MMI) 2.5 (weak).
Physical scale: An earthquake of magnitude 3.2 releases seismic energy equivalent to roughly 951 kg of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 97 m — a useful intuition for the size of the slip patch on the fault.
The epicenter is located in Alaska, a region characterized by Pacific Plate subduction beneath the North American Plate, producing frequent megathrust and crustal earthquakes along the Aleutian arc. The nearest mapped fault system is the Aleutian megathrust. View all earthquakes in Alaska.
Learn more: Magnitude scale · Aftershock sequences
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
Did You Feel It? — community-reported shaking
Aggregated felt-report intensity from 18 citizen responses to the USGS Did You Feel It? system. Each colored zone represents the average MMI from reports in that area.
Source: U.S. Geological Survey Did You Feel It?. View on USGS · submit your own report
Earthquake Details
-149.9623°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 3.2 earthquake near Point MacKenzie, Alaska?
The magnitude 3.2 earthquake that struck 1 km NNE of Point MacKenzie, Alaska on September 24, 2021 at 20:34 UTC had a depth of 43.3 km. It was felt by 18 people with maximum shaking intensity of MMI 2.5 (weak). For context, this was a minor earthquake typically detected only by instruments.
Where did the earthquake occur?
The earthquake epicenter was located at 61.3736°, -149.9623°, which is 1 km NNE of Point MacKenzie, Alaska. View all earthquakes in Alaska.
Were there aftershocks?
Aftershock activity is monitored continuously by the USGS. Aftershock sequences from magnitude 3.2 earthquakes can continue for several days and gradually diminish over time.
Has Alaska had earthquakes this big before?
The largest recorded earthquake in Alaska was the M9.2 Great Alaska earthquake of March 27, 1964. Today's magnitude 3.2 event is significantly smaller than that historical record.
Authoritative source: USGS event page (event ID: ak021c9wlq5g). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2021, September 24, 2021). M3.2 Earthquake 1 km NNE of Point MacKenzie, Alaska — September 24, 2021. Retrieved December 4, 2021 from https://www.earthquaketracker.org/earthquakes/event/ak021c9wlq5g/