M3.2 Earthquake 136 km SW of Adak, Alaska — December 16, 2020
2020-12-16 19:22:49 UTC (2020-12-16) · approx. 7:22 AM UTC-12 local
On December 16, 2020 at 19:22 UTC, a magnitude 3.2 shallow crustal earthquake struck 136 km SW of Adak, Alaska, at a depth of 35.0 km and coordinates 51.1496°, -178.2219°.
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.
This earthquake is part of an ongoing aftershock sequence following the magnitude 5.3 mainshock that occurred 23 days ago 151 km WSW of Adak, Alaska. Since the mainshock, the USGS has recorded 25 aftershocks in this area. Aftershock activity is expected to continue for days to weeks as stresses on surrounding faults redistribute.
Earthquake Details
-178.2219°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 3.2 earthquake near Adak, Alaska?
The magnitude 3.2 earthquake that struck 136 km SW of Adak, Alaska on December 16, 2020 at 19:22 UTC had a depth of 35.0 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 3.2 earthquakes can continue for several days and gradually diminish over time.
Is this the same earthquake as the M5.3 one earlier?
No. This magnitude 3.2 earthquake is an aftershock of the larger magnitude 5.3 mainshock that occurred earlier 151 km WSW of Adak, Alaska. Aftershocks are smaller earthquakes triggered by stress changes from the mainshock.
Actions
Understanding This Data
Magnitude 3.2 earthquakes are typically only recorded by instruments.
Authoritative source: USGS event page (event ID: us6000d20d). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2020, December 16, 2020). M3.2 Earthquake 136 km SW of Adak, Alaska — December 16, 2020. Retrieved February 27, 2021 from https://www.earthquaketracker.org/earthquakes/event/us6000d20d/