Eastern Tennessee Seismic Zone
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.
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 4.6 magnitude, occurring in 1973 near Knoxville, Tennessee and April 29, 2003 near Fort Payne, Alabama. Earthquakes large enough to be felt occur approximately once a year in the ETSZ. The U.S. Geological Survey estimates that earthquakes as large as magnitude 7.5 are possible in the ETSZ. Events of magnitude 5–6 are estimated to occur once every 200 to 300 years.
The source of seismic activity in the ETSZ is not known. The ETSZ is located far from edge of the North American continent 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. 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.
Earthquakes associated with the ETSZ have included:
- Irondale, Alabama, earthquake, October 18, 1916 (magnitude 5.1)
- 1973 Knoxville, Tennessee, earthquake (magnitude 4.6)
- April 29, 2003 earthquake near Fort Payne, Alabama (magnitude 4.6)
- November 10, 2012 earthquake near Whitesburg, Kentucky (magnitude 4.3)
- April 25, 2018 earthquake near Mascot, Tennessee (magnitude 2.7)
- April 29, 2018 earthquake near Varnell, Georgia (magnitude 2.6)
- April 29, 2018 earthquake near Morristown, Tennessee (magnitude 3.1)
- December 12, 2018 Southern Appalachian earthquake (magnitude 4.4)
- "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.
- 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.
- "Tennessee: Earthquake History". USGS. Retrieved July 13, 2015.
- Associated Press (November 12, 2012). "Geologists: Kentucky earthquake too deep to be spurred by region's mining, blasting". Fox News.
- "M 2.7 - 5km SW of Mascot, Tennessee". USGS. April 25, 2018. Retrieved April 29, 2018.
- "M 2.6 - 12km ENE of Varnell, Georgia". USGS. April 29, 2018. Retrieved April 29, 2018.
- "M 3.1 - 7km NW of Morristown, Tennessee". USGS. April 29, 2018. Retrieved April 29, 2018.
- "M 4.4 - 11km NNE of Decatur, Tennessee". USGS. December 12, 2018. Retrieved December 12, 2018.