Joint interpretation of electrical and seismic data aimed at modelling the foundation soils of the Maredolce monumental complex in Palermo (Italy)

Abstract

The monumental complex of Maredolce (Palermo) includes an Arab-Norman castle that stands on the banks of an artificial lake carved out of the calcarenitic rock that rests on impermeable clays. The lake was originally filled with water, thanks to the channelling of a spring. Over time, the lowering of the water table and the high hydraulic permeability of the calcarenites have caused the lake to dry up. A project to renovate the monumental complex has recently been launched. It also provides the study of a possible restoration of the original conditions of the lake. To this end, a multidisciplinary geophysical study was carried out to investigate the geotechnical conditions of permeability of the land outcropping and provides valid technical solutions for waterproofing the bottom of the lake. For this purpose, a joint interpretation was performed using data acquired with different geophysical techniques, such as seismic refraction tomography, electrical resistivity and induced polarization tomography, multichannel analysis of surface waves and horizontal-to-vertical spectral ratio of environmental vibration recording. Joint interpretation, supported by cluster analysis techniques, allowed the reconstruction of the geophysical and geotechnical model of the subsoil of the ancient lake, helpful to suggest appropriate techniques for waterproofing the bottom of the lake.