Geophysical surveys for detecting subsidence and collapse areas at Cardona salt diapir (Catalonia, Spain)

Subsidence and collapse are major problems associated with salt mining, causing damage to surface structures. These processes can be associated with different processes as compaction of natural sediments, ground water dewatering, natural terrain deformations and underground material exploitation. Many of these factors are natural and have a long period occurrence, while human intervention can start or accelerate some processes. Consequently, to avoid adverse impacts of subsidence and collapse, reliable prediction is essential. Barla and Jarre (1991), Bell (1992) and Marino (1999) have conducted studies dealing this subject. Around the Cardona salt mine major problems related to this facts occurs and geophysical methods have been applied in order to gain information about the hazardous areas. Gravity and EM methods have been carried out to detect potential collapse areas, while GPS levelling has been performed for subsidence control.