Georadar investigations in the central nave of Hagia Sofia, Istanbul (Turkey)

Within an interdisciplinary project to study Istanbul’s Hagia Sofia, a georadar survey was carried out in the central naveto assess if the deformations of the structure previously observed could be related to a differential behavior of the subsoilcaused by architectural remains underneath. This study faces an unusual challenge since it was necessary to study the space beneath the scaffolding placed for the restoration works. The survey of the central navewas successful and allowed the detection of remains of walls that probably formed the basement of a previous 18- by 22-m structure. In addition, another interesting feature was discovered 2 m below the marble mosaic in the southeastern part of the nave. Although it is not possible to define its function, it seems that there could be a close relationship between this 2- by 3-m buried structure and the marble mosaic in the floor surface. Although some structures were identified under the floor of Hagia Sofia, there are no major changes in the topography of the central navefloor.