Some tests of 3D ultrasonic traveltime tomography on the Eleonora d'Aragona statue (F. Laurana, 1468)

The use of a non-destructive technique in situ can be a valuable diagnostic tool to support verification of restoration, as well as a monitoring technique in works of art or historical monuments. We present a high resolution 3D ultrasonic tomography to one of the most important statues of the Regional Gallery of Palazzo Abatellis of Palermo, the bust of Eleonora d'Aragona by F. Laurana (1430–1502). This technique allowed to study the structural continuity of the material of the marble. Some tests have been carried out to optimize inversion parameters, such as voxel size and to choose between straight and curved rays. We propose to calculate a minimum lateral resolution using the sampling frequency instead of that of the probes. Consequently it was chosen to use a voxel size of 2 cm, lower than the expected resolution, 0.07 m (calculated considering the median ray length), and also to use curved rays instead of straight rays approximation. The resulting model showed velocity values corresponding to a sufficiently homogeneous and well-preserved marble, but in the lower front portion of the trunk at the breasts, that bears the entire weight of the artwork, low velocity values are present.