Seismological Monitoring of Rockfalls as a Tool to Study Weathering Processes at the Geoheritage Site Žebračka Mine in Mining District of Zlaté Hory (Czech Republic)

Abstract

Mining cultural monuments are very popular in the Czech Republic, and after the period of the mining activity reduction in the 1990s, when tens of mines were permanently closed, mining monuments are the last witnesses to mining activities in the areas. These are monuments of types of mine buildings, mining towers, and galleries. However, a monument that is beyond this list is the Žebracka Mine—a local sinkhole located in the Moravian-Silesian Region in the cadastral area of the municipality of Heřmanovice, but historically belonging to Zlate Hory. It is not an old monument, but since it is a local sinkhole, it is changing as a result of weathering when the rock falls from the overhang and the side of the mine. Since 2013, the mine has been monitored by 3D laser scanning, and since 2003 by seismological monitoring. This monitoring proves that it is still a living monument. The study evaluates a unique data series of registered seismic events related to the effect of the rockfalls covering the period of 16 years. The mutual confrontation of seismological data with atmospheric conditions, namely, outside air temperatures and precipitation, enabled to reveal the long-term development of the rockfall activity and to determine the influence of specific atmospheric parameters. The results show that the most extensive rockfall activity occurs at temperatures oscillating around the freezing point and is thus primarily related to the freezing and thawing of water in fissures of weathered parts of the rock mass. Understanding these processes is essential for forecasting the possible development of the sinkhole in the coming decades and for all other planned activities at the site related to its opening to tourists. In addition, the knowledge gained from the research will provide valuable information for educational purposes for visitors to the site, to understand the weathering processes taking place there, and to understand the behaviour of the geological environment in the given climatic conditions. Moreover, visitors will learn about current methods of monitoring the stability of the rock mass in situ. The planned opening of the sinkhole to tourists will be reflected in the increasing attractiveness of the region and will attract many enthusiasts in the field of mining history and geology, not only from the Czech Republic but also from nearby Poland.