Seismic refraction, isotropic anisotropic seismic tomography on an ancientmonument (Antonino and Faustina temple AD 141)

This paper describes the results of using geophysical techniques to investi gate three columns of the Pronaos of the Antonino and Faustina temple (AD 1 41) in Rome, Italy; the columns are of cipollino marble which shows alterna te sequences of mica and calcite beds. We applied seismic refraction using traditional interpretation, and seismic transmission tomography. The compar ison between the results of the refraction study and the 2D and 3D isotropi c tomographic analyses suggested anisotropic characteristics for the marble , and this prompted us to perform a further tomographic experiment, taking into account these characteristics of the material. Assuming an elliptical model, the main directions of anisotropy were detected. Two velocity fields corresponding to the main directions of the anisotropy were measured and a nomalies such as cracks and fractures were noted. The conjugate-gradient al gorithm was used to invert the data. The results of the isotropic and aniso tropic models were compared. The correlation between the methods highlighte d the characteristics of the marble, i.e. anisotropy, depth of the weatheri ng, fractures and small cracks. The results show that the material of the c olumns is in reasonable condition, with the exception of a surface area 6 c m to 15 cm deep that we estimate has been weathered for 2000 years, and tha t has been particularly affected by pollution in the last century.