Integrated geophysical surveys for the subsurface mapping of buried structures under and surrounding of the Agios Voukolos Church in İzmir, Turkey

This work presents the results of the integrated usage of geophysics in the Agios Voukolos Church, one of the unique Orthodox constructions in İzmir. The surveys had two main objectives: to define subsurface characteristics inside and around the church and search for possible structural damage such as cracks and fissures, that may exist in the subfloor of the church. Magnetic gradiometry, ground penetrating radar and electrical resistivity tomography were used in the investigations; this study is the first indoor application of magnetic gradiometry. The studies revealed that several suspicious relics and crypts might have existed under the floor of the church. In addition, investigations of the courtyard area indicated potential buried structures under the settling area of the church. This study demonstrates the importance of the integrated usage of non-destructive geophysical techniques in searching for possible hidden subsurface structures in standing historical buildings. In addition, magnetic gradiometry might be useful in indoor studies, assuming that there are no important magnetic sources near the site.

► The integrated use of geophysical techniques can be effective and useful in the investigation of indoor structures.
► This work demonstrates the importance of the integrated techniques in searching for possible hidden subsurface structures in standing historical buildings.
► This study is the first indoor application of magnetic gradiometry.
► Finally, the usage of combined geophysical techniques gives us a fairly complete and valuable model of the subsurface characteristics of historical buildings