Comment on “Seismic Tomographic Imaging of a Buried Concrete Target”

Abstract

Bishop and Styles are to be congratulated for attempting the difficult task of validating a tomographic reconstruction technique on the basis of a field experiment. However, in their closing remarks they state that "even when (they) had control of most parameters only moderate image qualities were obtained " ; we cannot agree that there was sufficient planning of the trial for it to represent a fair and objective test of geophysical seismic velocity tomography, as we discuss below.The paper is of particular interest because it highlights so effectively the need for careful planning and design before the implementation of a technique of this type. In particular, when searching for particular targets, the following points should be taken into consideration.

Seismic tomography: Application for archaeological purposes

“…These two techniques did not provide the precision required for measuring the first arrivals. Therefore, it was decided to verify the possibility of using the pseudo-arrivals, according to the definition of Bishop and Styles (1990), i.e., assuming that the first arrival is the time at which the signal intersects the time axis for the second time after the start of the oscillation (Figure 3b). With this technique, a delay is introduced that is equal to half of a wavelength and therefore is not constant in relation to distance.…”