Inventory of the geometric condition of inanimate nature reserve Crystal Caves in “Wieliczka” Salt Mine

Abstract

Geological structure of the salt rock mass and its more than 700-year-old exploitation make the “Wieliczka” Salt Mine an important monument of material and natural values. One of the most interesting objects in the mine are the Crystal Caves, which are globally unique, because of salt crystals (halite) which are covering ceiling and sidewalls. Due to its uniqueness, caves are protected by law and a subject of preventive measures. Because of the tightening forces of excavations (convergence) Crystal Caves must be periodically monitored. It is estimated that the speed of convergence is from 0 to 2 mm/year. In order to monitor changes in the geometry of the excavation and deformation of crystals in the 1960s of twentieth century photogrammetric measurements were performed. They require a lot of work and time, and adversely affect the microclimate in the Crystal Caves. Presented in the article modern geodetic measurement techniques (laser scanning, total station) allow to obtain comprehensive data in a short time. It helped to receive an accurate analysis of the changes in geometry of caves. Proposed in the article measurement procedure determines the range of research, which was carried out in order to fully monitor the tested object. Due to the estimated speed of convergence and the accuracy of the applied technologies measurement series on an annual basis are planned. Comparative analysis of the data obtained in the future, give specific conclusions about the current impact of the rock mass on the Crystal Caves and help to improve prevention.