Remigration of ground-penetrating radar data

Optimal electromagnetic wave propagation velocities and subsurface images for ground-penetrating radar (GPR) data can be specified by using an imaging scanning method. In addition to time-migrating the unmigrated GPR section, we remigrate the already time-migrated section by a one-step remigration operator using different velocities. This creates many time-migrated images for different constant migration velocities. In this way, the computation time for time-migration is very much reduced. Time-migrated reflector images 'propagate' when the constant migration velocity is continuously changed. For this 'propagation' there exists a wave-equation-type partial differential equation. Each time-migrated section can thus be viewed as a snapshot for a certain migration velocity. The time-migrated reflector images behave like 'waves', called image waves. This is applied to real GPR data acquired over a concrete body within which a steel cable flame is buried. The method produces a quick velocity scan to find a reliable migration velocity leading to the best time-migrated image. (C) 1999 Elsevier Science B.V. All rights reserved.