M4.4 Earthquake 138 km WSW of Adak, Alaska — September 3, 2020
2020-09-03 23:35:56 UTC (2020-09-03) · approx. 11:35 AM UTC-12 local
On September 3, 2020 at 23:35 UTC, a magnitude 4.4 shallow crustal earthquake struck 138 km WSW of Adak, Alaska, at a depth of 35.0 km and coordinates 51.2591°, -178.3754°.
Physical scale: An earthquake of magnitude 4.4 releases seismic energy equivalent to roughly 60 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 655 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 5.1 mainshock that occurred 27 days ago 149 km WSW of Adak, Alaska. Since the mainshock, the USGS has recorded 29 aftershocks in this area. Aftershock activity is expected to continue for days to weeks as stresses on surrounding faults redistribute.
Did You Feel It? — community-reported shaking
Aggregated felt-report intensity from 1 citizen response 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
-178.3754°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 4.4 earthquake near Adak, Alaska?
The magnitude 4.4 earthquake that struck 138 km WSW of Adak, Alaska on September 3, 2020 at 23:35 UTC had a depth of 35.0 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 4.4 earthquakes can continue for several days and gradually diminish over time.
Is this the same earthquake as the M5.1 one earlier?
No. This magnitude 4.4 earthquake is an aftershock of the larger magnitude 5.1 mainshock that occurred earlier 149 km WSW of Adak, Alaska. Aftershocks are smaller earthquakes triggered by stress changes from the mainshock.
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Understanding This Data
Magnitude 4.4 earthquakes are often felt but rarely cause damage.
Authoritative source: USGS event page (event ID: us7000bhj9). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2020, September 3, 2020). M4.4 Earthquake 138 km WSW of Adak, Alaska — September 3, 2020. Retrieved November 17, 2020 from https://www.earthquaketracker.org/earthquakes/event/us7000bhj9/