M4.3 Earthquake 226 km ESE of Attu Station, Alaska — March 30, 2023
2023-03-30 18:47:09 UTC (2023-03-30) · approx. 6:47 AM UTC+12 local
On March 30, 2023 at 18:47 UTC, a magnitude 4.3 shallow crustal earthquake struck 226 km ESE of Attu Station, Alaska, at a depth of 37.5 km and coordinates 52.0880°, 176.2767°.
Physical scale: An earthquake of magnitude 4.3 releases seismic energy equivalent to roughly 43 metric tons of TNT. Empirical fault-scaling laws (Wells & Coppersmith, 1994) estimate the subsurface rupture length at approximately 558 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 5.0 mainshock that occurred 8 days ago 231 km ESE of Attu Station, Alaska. Since the mainshock, the USGS has recorded 42 aftershocks in this area. Aftershock activity is expected to continue for days to weeks as stresses on surrounding faults redistribute.
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
Earthquake Details
176.2767°E
Technical Information
Nearby Earthquakes (Last 7 Days)
Common Questions
How strong was the magnitude 4.3 earthquake near Attu Station, Alaska?
The magnitude 4.3 earthquake that struck 226 km ESE of Attu Station, Alaska on March 30, 2023 at 18:47 UTC had a depth of 37.5 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 4.3 earthquakes can continue for several days and gradually diminish over time.
Is this the same earthquake as the M5.0 one earlier?
No. This magnitude 4.3 earthquake is an aftershock of the larger magnitude 5.0 mainshock that occurred earlier 231 km ESE of Attu Station, Alaska. Aftershocks are smaller earthquakes triggered by stress changes from the mainshock.
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Understanding This Data
Magnitude 4.3 earthquakes are often felt but rarely cause damage.
Authoritative source: USGS event page (event ID: us6000k0y3). All scientific values on this page are sourced verbatim from the USGS feed.
Cite this page: EarthquakeTracker.org. (2023, March 30, 2023). M4.3 Earthquake 226 km ESE of Attu Station, Alaska — March 30, 2023. Retrieved June 3, 2023 from https://www.earthquaketracker.org/earthquakes/event/us6000k0y3/