--> Gulf Coast Subsidence, Crustal Loading, Geodesy, and InSAR, Ronald Blom, Bruce Chapman, Roy Dokka, Eric Fielding, Erik Ivins, and Rowena Lohman, #90093 (2009)

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Gulf Coast Subsidence, Crustal Loading, Geodesy, and InSAR

 

 

Ronald Blom1, Bruce Chapman1, Roy Dokka2,

Eric Fielding1, Erik Ivins1, and Rowena Lohman3

 

1Jet Propulsion Laboratory, California Institute of Technology,

4800 Oak Grove Dr., Pasadena, California  91109

 

2Louisiana Spatial Reference Center and Center for GeoInformatics,

Louisiana State University, Baton Rouge, Louisiana  70803

 

 3Department of Earth and Atmospheric Sciences, Cornell University, Snee Hall, Ithaca, New York  14850

  

  

ABSTRACT

 

Hurricanes Katrina and Rita focused attention on the vulnerability of the U.S. Gulf Coast.  Several processes have been documented to contribute to this vulnerability, including wetland loss due to lack of present day sediment flux, land subsidence due to sediment compaction, sediment oxidation, fluid withdrawal, salt evacuation, tectonics, and also crustal loading.  Key to protection of lives and property are precise and accurate measurements of subsidence, and accurate predictions of future subsidence rates.  Towards these ends, we are contributing in two areas.  First, one of the least studied subsidence driving phenomena is the effect of crustal loading due to Mississippi River sediments, and the geologically recent ~130 m (427 ft) rise in sea level.  We model subsidence rates expected from these loads using methods developed for, and validated by, research on post-glacial rebound.  Our model predicted, and geodetically observed, vertical subsidence rates vary between 2-8 mm/yr (0.079-0.32 in/yr) over areas of 30,000 to 750 km2, respectively.  This viscoelastic flexure is the background crustal deformation field, upon which larger amplitude, but smaller spatial scale, subsidence occurs due to other factors.  Second, we seek to extend subsidence measurements from traditional geodetic techniques (including global positioning satellite [GPS]), to geographically comprehensive measurements derived from synthetic aperture radar interferometry (InSAR).  This technique uses sequential radar observations to construct interferograms which can be used to measure elevation changes.  The Gulf Coast is a very challenging environment for InSAR techniques and we are developing new persistent scatterer methods, and also will make new observations with UAVSAR (Uninhabited Aerial Vehicle Synthetic Aperture Radar, which at present flies on a crewed aircraft), a new airborne interferometer system.  Here we review work to date and plans for integration of UAVSAR data. 

 

 

Blom, R., B. Chapman, R. Dokka, E. Fielding, E. Ivins, and R. Lohman, 2009, Gulf Coast subsidence, crustal loading, geodesy, and InSAR:  Gulf Coast Association of Geological Societies Transactions, v. 59, p. 101-114.

 

AAPG Search and Discover Article #90093 © 2009 GCAGS 59th Annual Meeting, Shreveport, Louisiana