2pUW5. Measurement and localization of interface wave reflections from buried objects.

Session: Tuesday Afternoon, May 14

Time: 2:20

Author: Eric Smith
Author: Preston S. Wilson
Author: Fred W. Bacon
Author: Jason F. Manning
Author: John A. Behrens
Author: Thomas G. Muir
Location: Appl. Res. Labs., Univ. of Texas, Austin, TX 78713-8029


It is demonstrated that interface wave reflections from buried objects can be created with an active seismic interface wave sonar, and measured and localized on a seismic array. The sonar reported here was implemented on a natural beach of the Gulf of Mexico. It employs a monostatic source/receiver geometry with a three-element horizontal receiving array, in which each element is a triaxial geophone (velocimeter). Detailed measurements of propagation loss at the site make it possible to compare reflected signal power with the results of predictions computed in first order, pointlike-scatterer perturbation theory. These propagation measurements, together with phase information, verify that the reflections are interface waves, and measured values agree well with predictions, within experimental and theoretical errors, both of which are well constrained and small. Simulated data are used to compare a beam pattern at uniform shading with experimental results, and it is found that nonuniform shading in the experimental data produces closest correspondence. Independently performed ground truthing and reverberation analysis further provide a consistent and thorough picture of the background sound fields from which these echos must be extracted. [Work supported by the Office of Naval Research.]

from ASA 131st Meeting, Indianapolis, May 1996