Improved GPR interpretation through resolution of lateral velocity heterogeneity: Example from an archaeological site investigation

In a typical common-offset ground-penetrating radar (GPR) survey, lateral velocity contrasts may go undetected leading to misinterpretation. Resolution of lateral velocity heterogeneity requires multi-fold acquisition and analysis. Further, pre-stack depth migration (PSDM) is required to produce accurate images in the presence of large lateral velocity gradients. In an archaeological investigation conducted near Boise, Idaho, we delineated a portion of what we interpret to be an abandoned dump site. Using multi-fold acquisition with reflection tomography,we identified an abrupt lateral velocity increase of similar to 40% resulting in a substantial velocity pull-up in the time domain. PSDM corrected for the velocity pull-up enabling a more accurate interpretation and identification of additional structures of potential historical significance. The migration velocity model provided additional constraints on materials which enhanced our understanding of the subsurface. (C) 2008 Elsevier B.V. All rights reserved.