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The Eastern Tennessee seismic zone (ETSZ), also known as the East Tennessee seismic zone and the Southern Appalachian seismic zone, is a geographic band stretching from northeastern Alabama to southwestern Virginia that is subject to frequent small earthquakes. The ETSZ is one of the most active earthquake zones in the eastern United States.^[1]^[2]

Seismicity

Most earthquakes in the ETSZ are small and are detected only with instruments. A few damaging earthquakes have occurred in the ETSZ; the largest historic earthquakes measured 5.1 magnitude, occurring in April 29, 2003 near Fort Payne, Alabama and August 9, 2020 near Sparta, North Carolina. Earthquakes large enough to be felt occur approximately once per year in the ETSZ.^[1] The United States Geological Survey estimates that earthquakes as large as magnitude 7.5 are possible in the ETSZ. Even though Oak Ridge, Tennessee experiences these earthquakes, the nuclear reactors in the city are rated to handle 8.0 magnitude earthquakes. So, if a 7.5 magnitude earthquake were to occur, a meltdown would be highly unlikely. Events of magnitude 5–6 are estimated to occur once every 200 to 300 years.^[3]

Source

The source of seismic activity in the ETSZ is not known. The ETSZ is located far from edge of the North American plate and represents a mid-continent or intraplate earthquake zone. The known faults in the ETSZ are generally ancient; no known active faults reach the surface.^[1] Research published in 2010 indicates a correlation between the Eastern Tennessee seismic zone and the New York–Alabama Lineament and suggests that earthquakes in the seismic zone originate at depth in metasedimentary gneiss.^[4]

References

^ ^a ^b ^c "M4.6 Fort Payne, Alabama Earthquake of 29 April 2003" (PDF). Prepared by U.S. Geological Survey National Earthquake Information Center. 13 June 2003. Archived from the original (PDF) on 4 January 2011.
^ "Seismic Zones Affecting Alabama". Geological Survey of Alabama; Geologic Hazards Program. Archived from the original on 3 January 2011.
^ "How likely is an earthquake?". Alabama Emergency Management Agency. Archived from the original on 2013-04-25. Retrieved 2012-11-12.
^ Steltenpohl, Mark G.; Zeitz, Isidore; Horton, J. Wright Jr.; Daniels, David L. (27 January 2010). "New York–Alabama lineament: A buried right-slip fault bordering the Appalachians and mid-continent North America". Geology. 38 (6): 571–574. Bibcode:2010Geo....38..571S. doi:10.1130/G30978.1.