Two decades of GPS/GNSS and DInSAR monitoring of Cardona salt mines (NE of Spain) – natural and mining-induced mechanisms and processes

Xavier Rodriguez-Lloveras,Carolina Puig-Polo,Jordi Marturià,Jose A. Gili,Nieves Lantada

doi:10.5194/piahs-382-167-2020

Abstract

Abstract. Cardona area presents surface rising and subsidence active movements. In 1999 a series of sinkholes appeared due to the infiltration of Cardener River water into the mine tunnels, damaging surface infrastructures. Since then, high precision GNSS/GPS was used annually to position a network of 40 points spread over the area. GNSS/GPS work is carried out with the Fast-Static (FS) method. Additionally the surface movements have been monitored with satellite Differential Interferometry Synthetic Aperture Radar (DInSAR). Results indicate that the movement has a complex spatial distribution although consistent along time. Some areas show surface rising during the last two decades, while other areas show subsidence. The use of the two techniques allowed to determine the most plausible causes of these movements generated by a set of interwoven natural and human-induced complex processes.

Highlights

Cardona is a town located at the north-west of the province of Barcelona, on the area known as the Conca Potàssica Catalana (Potash Basin or CK), which is a great saline unit part of the evaporitic lithologies of the region known as Central Catalan Depression, part of the Ebro River Depression (NE Spain; Fig. 1).CK origin is a consequence of the evaporation of an inner sea 40 million years ago, during the upper Eocene
In Differential Interferometry Synthetic Aperture Radar (DInSAR) data higher or lower punctual displacements are masked by the general pixel movement, while GNSS/GPS and levelling control points might be in locations with higher or lower movement than its surroundings
5 Conclusions In Cardona area the movements induced by natural and mining-induced processes have been monitored during the last two decades with two main techniques: GNSS/GPS and DInSAR. Results obtained with both methodologies are compatible in location trend and magnitudes, allowing detection of two main areas with inverse significant movements

Summary

Introduction

Cardona is a town located at the north-west of the province of Barcelona, on the area known as the Conca Potàssica Catalana (Potash Basin or CK), which is a great saline unit part of the evaporitic lithologies of the region known as Central Catalan Depression, part of the Ebro River Depression (NE Spain; Fig. 1).CK origin is a consequence of the evaporation of an inner sea 40 million years ago, during the upper Eocene. In this epoch this area was under marked subsidence being one of the deepest zones of the former sea This condition, combined with the active tectonics of the Alpine orogeny, led to the formation of a lagoon connected with the Atlantic ocean, which dried in time due the warm and tropical climate, leading to a mass crystallization of gypsum and saline units (the latter being composed by an alternation of potash salts layers, mainly sylvinita and carnalita (Marín y Bertrán de Lis, 1923; Monzón et al, 1989). Sodium salts were intensively used for the production of plastics, bleach, soap, glass, and so on, whereas potassium salts

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Conclusion