BATON ROUGE GEOLOGICAL SOCIETY

 

Paleoliquefaction features formed by seismic events originating from the New Madrid Seismic Zone

 

 

 

 

 

 

 

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The New Madrid seismic zone (NMSZ) was responsible for the highest-magnitude earthquakes to affect Louisiana in recorded history, comprising several events spanning December 1811 and January 1812. In the past two decades, research into preserved structures formed by liquefied water-saturated sediment in response to past seismic events has produced abundant literature documenting such paleoliquefaction structures produced by the 1811-1812 events and by prehistoric events in the NMSZ. Until recently, the extent of known paleoliquefaction structures extended southward from the NMSZ and terminated fairly definitely near the latitude of Memphis. More recently, however, one type termed a sand blow was identified and excavated in southern Richland Parish in northeastern Louisiana by Randel Tom Cox of the University of Memphis. Cox gave presentations on his discovery and the results of his excavation at annual conferences of the Association of Environmental & Engineering Geologists in New Orleans in September of 2008 and at the joint annual conference of the Gulf Coast Association of Geological Societies and the Geological Society of America in October of 2008. The abstract of the latter paper (by Cox and Gordon, submitted months earlier and prior to the beginning of the Richland Parish excavation) mentions other features identified in Morehouse and northern Franklin parishes, and may be accessed at: http://a-c-s.confex.com/crops/2008am/webprogram/Paper47937.html

References
Cox, R., 2008, Liquefaction in north Louisiana and south Arkansas and possible earthquake sources: Association of Environmental & Engineering Geologists, annual meeting, New Orleans, Symposium 3, "Seismic sources in the central U.S.: is New Madrid all there is?," September 18, 2008.
Cox, R., and J. Gordon, 2008, Sand blows on late Quaternary surfaces in northeast Louisiana [abstract]: Gulf Coast Association of Geological Societies and Geological Society of America, joint annual meeting, Houston, General Discipline Sessions/Structural Geology/Tectonics/Neotectonics/Paleoseismology (Posters), abstract 147-7, October 5, 2008.