Lee County Arkansas Incorporated and Unincorporated areas Marianna Highlighted

The Marianna Fault is a fault located in the

Crowley's Ridge Crowley's Ridge (also Crowleys Ridge) is a geological formation that rises 250 to above the alluvial plain of the Mississippi embayment in a line from southeastern Missouri to the Mississippi River near Helena, Arkansas. It is the most pro ...

area west of Marianna in eastern

Arkansas Arkansas ( ) is a landlocked state in the South Central United States. It is bordered by Missouri to the north, Tennessee and Mississippi to the east, Louisiana to the south, and Texas and Oklahoma to the west. Its name is from the O ...

. The discovery was first announced by seismologists on January 21, 2009. It is separate from the

New Madrid Seismic Zone The New Madrid Seismic Zone (), sometimes called the New Madrid Fault Line, is a major seismic zone and a prolific source of intraplate earthquakes (earthquakes within a tectonic plate) in the Southern and Midwestern United States, stretching t ...

, which is to the east. Haydar Al-Shukri, director of the Arkansas Earthquake Center at the University of Arkansas at Little Rock, discovered the Marianna Fault after searching for a fault since 2005. The fault line is seven miles long, with dimensions. The land above the Marianna Fault is mostly

cotton Cotton is a soft, fluffy staple fiber that grows in a boll, or protective case, around the seeds of the cotton plants of the genus '' Gossypium'' in the mallow family Malvaceae. The fiber is almost pure cellulose, and can contain minor pe ...

fields, but the presence of fertile soil with stretches of fine sand alerted seismologists to the fault's existence. It is believed that the Marianna Fault has previously experienced an

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, fr ...

that would have measured 7.0 on the

Richter magnitude scale The Richter scale —also called the Richter magnitude scale, Richter's magnitude scale, and the Gutenberg–Richter scale—is a measure of the strength of earthquakes, developed by Charles Francis Richter and presented in his landmark 1935 ...

, and may well do so again. Al-Shukri believes that the fault was created 5,000 years ago. Previously, the predicted earthquake damage Marianna, Arkansas might receive from the more distant New Madrid Fault suffering a 7.0 earthquake was 100% architectural and content damage, half of all bridges suffering some damage, 2,955 displaced residents, and loss of phones and electricity. The capital city of Arkansas,

Little Rock ( The "Little Rock") , government_type = Council-manager , leader_title = Mayor , leader_name = Frank Scott Jr. , leader_party = D , leader_title2 = Council , leader_name2 ...

, would also face damage. A major natural gas pipeline is located near the fault, and could be devastated by any such earthquake.

Tennessee Tennessee ( , ), officially the State of Tennessee, is a landlocked state in the Southeastern region of the United States. Tennessee is the 36th-largest by area and the 15th-most populous of the 50 states. It is bordered by Kentucky to th ...

and

Mississippi Mississippi () is a state in the Southeastern region of the United States, bordered to the north by Tennessee; to the east by Alabama; to the south by the Gulf of Mexico; to the southwest by Louisiana; and to the northwest by Arkansas. Miss ...

would possibly be affected as well. In 2006, a letter to the ''Seismological Research Letters'' indicated the possible existence of a fault at Marianna. Sand blows in the area were similar in size to the New Madrid sand blows, giving rise to the speculation of a new fault. It was believed that the Marianna sand blows were created between 5,000 and 7,000 years ago. This followed a letter to the same journal a few months before saying that

ground-penetrating radar Ground-penetrating radar (GPR) is a Geophysics, geophysical method that uses radar pulses to Geophysical imaging, image the subsurface. It is a non-intrusive method of surveying the sub-surface to investigate underground utilities such as concrete, ...

(GPR) was being used to study "large elliptical sand deposits" near Marianna. Haydar Al-Shukri announced the discovery of the Marianna Fault on January 21, 2009. Days later, Al-Shukri stated that more funding was required to study the fault, which would include trying to establish whether or not the fault was still active. The lack of seismic equipment in the vicinity is one factor in the need for additional funding. The most recent earthquake activity in the area around the fault was located ten miles northeast of Marianna in August 2008. It measured 2.6 on the Richter scale. Few quakes have been felt in the area since 1994.

References

{{Faults Geology of Arkansas Seismic faults of the United States Crowley's Ridge