AGU: Geophysical Research Letters

 

Editors' Highlight

Subsidence and southward displacement of southeastern Louisiana through normal faults

Tectonic processes such as faulting and load-induced flexure of the lithosphere have played a substantial role in lowering the land surface in the Gulf of Mexico basin over geologic time. Dokka et al. (2006) studied GPS data collected between 1995 and 2006 and found that Louisiana, including New Orleans and the larger Mississippi River delta, are both subsiding vertically and moving southward with respect to North America. They hypothesize that this subsidence occurs in part because the area is situated on the hanging wall of a normal fault system separating North America from deltaic sediments. These sediments and underlying bedrock are moving southward due to gravity instabilities created by sediments of the Mississippi River delta loading the Earth's crust and mantle, and by rising sea levels during continental glacial retreat. Because New Orleans, and other communities of southeastern Louisiana hit hard by hurricanes Katrina and Rita, lie atop this active fault system, the authors noted that future motion of this land should be considered during the reconstruction of the region.

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