Interrogating Levees in Texas, New Mexico, and New Orleans Using Various Seismic Methods

Compressional(Vp) and shear-wave (Vs) velocities were determined within earthen levees on the Rio Grande River in south Texas, south New Mexico and New Orleans. A loosely fitting relationship was developed to better characterize the internal condition of the levees. Seismic data were incorporated with surface observations, existing core taken from the levee, and airborne EM data acquired. Several different components of the seismic wavefield were recorded at each levee site. Several seismic data-analysis techniques were appraised including, Pand S-wave refraction, Pand S-wave refraction tomography, Rayleigh and Love-wave surface-wave analysis using multi-channel analysis of surface waves (MASW), and Pand S-wave cross-levee tomography. In addition, at each of the sites compressional(Vp) and shear-wave (Vs) velocity changes were measured. Each of the levee sites had a unique seismic response that was related to levee material, shape, velocity model, and time of the evaluation (most likely related to varying moisture content). Clearly, no one property relationship to characterize levees can be established for all levee systems, each needing a unique norm defined.