Preliminary ERT surveys at the St. Salvatore fortress in the St. Raineri peninsula, Messina (Italy)
by
F. Giannino
Osservatorio Sismologico, University of Messina, Via Osservatorio, 4, 98121 Messina, Italy.
Coauthors: De Domenico D. (1), Teramo A. (1), Bottari A. (1), Carveni P. (2), Ministeri A. (3). (1) Osservatorio Sismologico, University of Messina, Via Osservatorio, 4 – 98121 Messina, Italy. (2) Dipartimento di Scienze Geologiche, University of Catania,Corso Italia, 55 – 95129 Catania, Italy. (3) Cultural and Environmental heritage office, Messina Italy.

A geoelectrical prospection campaign has been led in one of the sites that characterizes the ancient city of Messina better. Built about 1500, in the extreme part of a scythe-shaped geological structure, the St. Salvatore fortress consists of some thick walls (4 m.) having a maximum length of about 100 m. and including the St. Anna tower, a circle-shaped masonry building whose original structure dates as far as 1100.

Measurements were undertaken on a 3D grid in correspondence of the wall located in the north border of the fortress and a line along an alignment parallel to this as well, starting with the east side wall of the St. Anna tower.

Data has been acquired with a multielectrode device allowing 28 electrodes in a Wenner-Schlumberger and dipole-dipole configuration to be used; for the 3D grid, an interelectrodic distance and a lateral offset of 2 m and 4 m, respectively, were chosen, while, along the line parallel to the 3D grid a 4 m electrode spacing was used. The goal of these preliminary investigations, leading to the geotechnical and geological characterisation of the whole area, is related to a planned geotechnical vulnerability analysis that has to be linked to another more specific one, the seismic one of the St. Anna tower, on which a 50 m high stele has been erected.

The achieved results allow a positive consistency verification with the drillings carried out. Furthermore, it has to be noticed that two high resistive zones, separated by a more conductive one, coherent with the presence of a fault having a NW/SE direction and a high fracture level of the wall foundations in correspondence with the surface of the external part of the fortification wall as well, have been highlighted.

Date received: September 23, 2004

Copyright © 2004 by the author(s). The author(s) of this document and the organizers of the conference have granted their consent to include this abstract in Atlas Conferences Inc. Document # caon-65.