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
(We dare defend our rights)
, anthem = " Alabama"
, image_map = Alabama in United States.svg
, seat = Montgomery
, LargestCity = Huntsville
, LargestCounty = Baldwin County
, LargestMetro = Greater Birmingham
, area_total_km2 = 135,7 ...
to southwestern
Virginia
Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the East Coast of the United States, Atlantic Coast and the Appalachian Mountains. The geography an ...
that is subject to frequent small
earthquake
An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from ...
s. The ETSZ is one of the most active earthquake zones in the eastern United States.
Earthquake magnitude
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
Knoxville is a city in and the county seat of Knox County in the U.S. state of Tennessee. As of the 2020 United States census, Knoxville's population was 190,740, making it the largest city in the East Tennessee Grand Division and the state ...
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.
]
Seismic source
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 In geology, anorogenic magmatism is the formation, intrusion or eruption of magmas not directly connected with orogeny (mountain building). Anorogenic magmatism occurs, for example, at mid-ocean ridges, hotspots and continental rifts. This contrast ...
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
Gneiss ( ) is a common and widely distributed type of metamorphic rock. It is formed by high-temperature and high-pressure metamorphic processes acting on formations composed of igneous or sedimentary rocks. Gneiss forms at higher temperatures a ...
.
Seismic events
Earthquakes associated with the ETSZ have included:
* Irondale, Alabama, earthquake, October 18, 1916 (magnitude 5.1)
* 1973 Knoxville, Tennessee
Knoxville is a city in and the county seat of Knox County in the U.S. state of Tennessee. As of the 2020 United States census, Knoxville's population was 190,740, making it the largest city in the East Tennessee Grand Division and the state ...
, earthquake (magnitude 4.6)
* April 29, 2003 earthquake near Fort Payne, Alabama (magnitude 4.6)
*December 12, 2018 earthquake north of Decatur, TN and east of Watts Bar Dam (magnitude 4.4 with smaller aftershocks)
* August 9, 2020 earthquake
An earthquake (also known as a quake, tremor or temblor) is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in intensity, from ...
south of Sparta, NC (magnitude 5.1 with small aftershocks)
* October 31, 2020 earthquake 4 miles north-west of Greeneville, TN
Greeneville is a town in and the county seat of Greene County, Tennessee, United States. The population as of the 2020 census was 15,479. The town was named in honor of Revolutionary War hero Nathanael Greene, and it is the second oldest tow ...
(magnitude 2.1)
* February 12, 2021 two earthquakes in the Tri-Cities region. One occurred roughly 5.6 miles north-north east of Richlands, Virginia. (magnitude 2.9) The second occurred a few miles south of Erwin, Tennessee. (magnitude 2.5)
See also
* Geology of Alabama
* Geology of Georgia
* Geology of Tennessee
* Geology of the Appalachians
* Virginia Seismic Zone
References
External links
Center for Earthquake Research and Information, University Of Memphis
{{coord missing, Tennessee
Earthquakes in Tennessee
Geology of Alabama
Geology of Georgia (U.S. state)
Geology of Tennessee
Geology of Virginia
Seismic zones of the United States