Document Type


Publication Date



tectonics, faulting, subsidence

Digital Object Identifier (DOI)


GPS data collected between 1995 and 2006 suggest that southeast Louisiana, including New Orleans and the larger Mississippi Delta, are both subsiding vertically and moving southward with respect to stable North America. Both motions are likely related due to their common tectonic setting. Subsidence in the New Orleans area occurs in part because it is located in the hanging wall of a large listric normal fault system that forms the northern boundary of a 7–10 km thick allochthon that is detached from stable North America. Southward motion of this allochthon relative to stable North America occurs at 2.2 ± 0.6 mm/yr. The average subsidence rate for GPS sites located on the allochthon is 5.2 ± 0.9 mm/yr relative to Earth's center of mass, or ∼7 mm/yr relative to mean sea level. Motion of the allochthon is likely due to the gravity instability created by rapid Holocene sediment deposition in the delta following continental glacial retreat and is facilitated at depth by weak salt horizons. Because New Orleans and other communities of southeastern Louisiana lie atop this active allochthon, future motion of this body should be considered during rebuilding of the region following Hurricanes Katrina and Rita.

Was this content written or created while at USF?


Citation / Publisher Attribution

Geophysical Research Letters, v. 33, issue 23, art. L23308

Copyright 2006 by the American Geophysical Union.

readme.txt (3 kB)
Table S1.txt (8 kB)
Table S1. Velocities of GPS sites in the northern Gulf Coast with respect to IGb00 and residual velocities after removal of the motion of stable North America.

Figure S1.eps (1139 kB)
Figure S1. Coordinate time series for CGPS site HAMM in IGb00.

Figure S2.eps (752 kB)
Figure S2. Coordinate time series for CGPS site 1LSU in IGb00.

Figure S3.eps (618 kB)
Figure S3. Coordinate time series for CGPS site HOUM in IGb00.

Figure S4.eps (765 kB)
Figure S4. Coordinate time series for CGPS site LMCN in IGb00.

Figure S5.eps (176 kB)
Figure S5. Coordinate time series for EGPS site FEMS in IGb00.

Figure S6.eps (174 kB)
Figure S6. Coordinate time series for EGPS site HEND in IGb00.

Figure S7.eps (1236 kB)
Figure S7. Coordinate time series for CGPS site KJUN in IGb00.

Figure S8.eps (1029 kB)
Figure S8. Coordinate time series for CGPS site WNFL in IGb00.