2-D and 3-D processing and interpretation of multi-fold ground penetratingradar data: a case history from an archaeological site

A 2.5-D and 3-D multi-fold GPR survey was carried out in the Archaeological Park of Aquileia (northern Italy). The primary objective of the study was the identification of targets of potential archaeological interest in an ar ea designated by local archaeological authorities. The second geophysical o bjective was to test 2-D and 3-D multi-fold methods and to study localised targets of unknown shape and dimensions in hostile soil conditions. Several portions of the acquisition grid were processed in common offset (CO), com mon shot (CSG) and common mid point (CMP) geometry. An 8 X 8 m area was stu died with orthogonal CMPs thus achieving a 3-D subsurface coverage with azi muthal range Limited to two normal components. Coherent noise components we re identified in the pre-stack domain and removed by means of FK filtering of CMP records. Stack velocities were obtained from conventional velocity a nalysis and azimuthal velocity analysis of 3-D pre-stack gathers. Two major discontinuities were identified in the area of study. The deeper one most probably coincides with the paleosol at the base of the layer associated wi th activities of man in the area in the last 2500 years. This interpretatio n is in agreement with the results obtained from nearby cores and excavatio ns. The shallow discontinuity is observed in a part of the investigated are a and it shows local interruptions with a linear distribution on the grid. Such interruptions may correspond to buried targets of archaeological inter est. The prominent enhancement of the subsurface images obtained by means o f multi-fold techniques, compared with the relatively poor quality of the c onventional single-fold georadar sections, indicates that multi-fold method s are well suited for the application to high resolution studies in archaeo logy. (C) 1999 Elsevier Science B.V. All rights reserved.