Karst Imaging Using a Fuzzy C-Means Data Clustering Approach (Montgrí Massif, Spain)

Identification of karst zones can be critical for hydrogeological or geotechnical studies. We present a case study carried out at the carbonate coastal Montgrí Massif (Spain) characterized by a well-developed karst system. The karst is covered by Quaternary sediments in the study area. The objective of the work is to image karst structures using geophysical techniques. Both electrical resistivity and seismic tomography (ERT and SRT) datasets have been acquired on five collocated profiles. Karst filled with clays produce seismic and electrical signature difficult to interpret. The Fuzzy c-means (FCM) data clustering approach is a way of producing an integrated model that can help to constrain lithological interpretation. In this study, FCM has been applied as a first step to one of the profiles with available ground-truthing from a near borehole. The resulting zonal model and cluster distribution has been used to interpret the integrated models obtained from applying FCM data clustering to the five datasets as a group. In this way, karst areas have been identified in three of the profiles in the near surface.