Multiple Geophysical Studies At The Urban Central Environment Of Athens In Connection With The Construction Of The Metro’S Main Station

Two main objectives were set to the personnel of the Laboratory of Geophysics of Patras University<br>and of the company Geome Ltd. by the scientists of the consortium of companies who were interested<br>in exploring a ten hectare area in the most central part of Athens. The objectives were, the location<br>of public utility networks unknown to the archives of the city and possible geological unconformities.<br>The case of the public networks was twofold. Firstly, it was important to know in advance of any<br>engineering and /or excavation procedure, the location of any network of pipes in order to avoid<br>damages which could raise the cost of the venture but they would not have consequences on the<br>public. Secondly, and more important, it was absolutely necessary to locate forgotten fragments of<br>gas pipes which have been installed in the past and which probably had trapped gas for ages. It is<br>understood that this case could be extremely dangerous for anybody who would operate for whatever<br>reason in close distance in connection with these buried pipes. In order to answer these questions a<br>magnetic gradiometer, a conductivity meter and a ground penetrating radar were utilized. The study<br>of the site for locating possible geological unconformities, involved resistivity measurements with<br>Schlumberger soundings, from which vertical parallel geoelectric sections could be produced, along<br>the main axis of the main avenue. On the same transects the antenna of the 80 MHz of the ground<br>penetrating radar was utilized.. The geophysical approach was fruitful by pin pointing a variety of<br>ferro-mettalic objects, geological contacts and a sub-terranean river.