Monday, November 15, 2010

Tennessee Earthquake History


Earthquake History

The western part of Tennessee was shaken strongly by the New Madrid, Missouri, earthquake of 1811 - 1812 and by earthquakes in 1843 and 1895. The area has also experienced minor shocks. Additional activity has occurred in the eastern part of the State, near the North Carolina border.
The three great earthquakes that occurred in the Upper Mississippi region near New Madrid in 1811 - 1812 rank among the most significant events in U.S. history. maximum intensity for each of the large shocks is estimated at XII. Topographic changes were noted over an area of 75,00 to 130,00 square kilometers; the total area shaken was at least 5 million square kilometers. Damage was very small for such great earthquakes because of sparse population. Chimneys were knocked down in many places in Tennessee, Kentucky, and Missouri. The most seriously affected area was characterized by raised and sunken lands, fissures, sinks, sand blows, and large landslides. The most typical sunken land is Reelfoot Lake in Tennessee. This lake is from 12 to 16 kilometers in length and from 3 to 5 kilometers in width. The submergence ranged from 1.5 to perhaps 6 meters, although greater depths were reported.
On January 4, 1843, a severe earthquake (intensity VIII) affected Memphis and other places in western Tennessee. The shock was reported to have lasted 2 minutes, though this is probably exaggerated. Walls were cracked, chimneys fell, and windows were broken. The total felt area was about 1 million square kilometers. The shock was strongly felt in Knoxville and caused considerable alarm but did no damage. It was also sharply felt in Nashville. Another tremor on November 28, 1844, caused some bricks to fall from chimneys in Knoxville (VI). Windows and dishes rattled and sounds like distant thunder were heard. Memphis experienced additional damage from a July 19, 1895, earthquake. Walls and chimneys cracked, and people were in panic (VI).
A strong shock centered at Knoxville on March 28, 1913, was felt over an area of 7,000 square kilometers in eastern Tennessee. Two shocks were felt in many places. Movable objects were overthrown, and bricks fell from chimneys (VII). A number of false alarms were set off at fire stations.
Buildings throughout the city shook violently. The Knox County Courthouse, a massive brick structure, trembled noticeably. People outdoors experienced a distinct rise and fall in the ground; there were some cases of nausea.
Another earthquake in the Mississippi Valley region caused damage in Tennessee and Arkansas on May 7, 1927. It was strongest at Jonesboro, Arkansas, where some chimneys fell (VII). However, the felt area indicated that the epicenter was farther to the east, in Tennessee. Damage there was limited to the shattering of window panes and breaking of dishes in the Memphis area. Many people were awakened by the early morning (2:28 AM) rapid rocking motion; in addition, surface and subterranean sounds were heard. The shock was also felt in parts of Alabama, Illinois, Kentucky, Mississippi, and Missouri, an area of about 337,000 square kilometers.
A sizable area in western Tennessee was affected by a fairly strong earthquake centered near Covington on November 16, 1941. Cracks appeared in the courthouse at Covington, where the tremor was noticed by everyone (V-VI). At Henning, it was felt by many, and an explosive noise preceded the trembling. The shock was also felt at Dyersburg, Frayser, Memphis, Millington, Pleasant Hill, and Ripley.
Dyersburg was the center of another disturbance on July 16, 1952. The press reported numerous cracks in a concrete-block structure. The earthquake was felt by nearly all, and many persons were frightened (VI). It was also felt at Finley and Jenkinsville. A weak aftershock was felt by a few people.
An earthquake centered near the Arkansas - Tennessee border (near Finley) awakened many residents on January 25, 1955. The 1:24 AM shock broke windows and damaged plaster walls at Finley, where it was felt by all (VI). The total felt area, including points in Illinois and Kentucky, covered about 75,000 square kilometers.
An early morning shock (3:02 AM) on March 29, 1955, was felt by everyone in Finley (VI). Plaster was cracked in one home. A roaring noise and violent shaking were reported. The tremor was felt by many at Caruthersville, Missouri.
Minor damage occurred at Covington from a January 28, 1956, earthquake. Chimneys and walls were cracked (VI). Many were awakened at Covington, and the press reported some residents left their homes at Henning. The shock was also felt in Arkansas and Missouri. Two tremors about 13 minutes apart were felt over a broad area of eastern Tennessee and adjoining parts of Kentucky, North Carolina, and Virginia on September 7, 1956. At Knoxville, both shocks were felt by nearly all, many of whom were alarmed (VI). Windowpanes shattered, dishes broke, objects were shaken from shelves, pictures fell, and some plaster was knocked from walls. The total felt area covered approximately 21,500 square kilometers.
An earthquake sequence consisting of one foreshock, a magnitude 4.6 main shock, and more than 30 aftershocks occurred south of Knoxville during the latter part of 1973. The foreshock, magnitude 3.4, on October 30, was felt over an area of 2,100 square kilometers, with a maximum intensity of V. The main shock cause minor damage (VI) in several towns in eastern Tennessee, Georgia, Kentucky, and North Carolina. Minor cracks in walls at the University of Tennessee Hospital at Knoxville were reported. Minor damage to walls, windows, and chimneys occurred in the Maryville - Alcoa area. The shock disrupted relay contacts at the Alcoa switching station, causing a temporary loss of power. The total felt area, including parts of South Carolina, Virginia, and West Virginia, as well as the region mentioned above, covered about 65,000 square kilometers. A network of eight portable seismographs was installed in the main epicentral area. This network was operational from December 2 through December 12 and recorded 30 small magnitude aftershocks. Additional aftershocks were reported felt on December 13, 14, and 21.
Abridged from Earthquake Information Bulletin, Volume 9, Number 2, March - April 1977. 

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