Although the Sudetes are considered tectonically stable, research conducted in the Niedźwiedzia Cave in Kletno by dr. Jacek Szczygieł, from our institute, indicates that at least 5 strong earthquakes (M>6) have occurred in the eastern Sudetes during the last 300 thousand years. This record was reconstructed mainly thanks to radiometric dating of damaged speleothems, but due to laboratory tests carried out together with Dr. Maciej Mendecki (also from IoES) on destroyed speleothems. According to the modeling, the most likely seismic source was the Sudeten Marginal Fault. However, reactivation of the faults cutting the cave cannot be ruled out, as kinematic analysis of these faults indicated their late Cenozoic activity. The research was conducted in cooperation with Dr. Artur Sobczyk (IGS UoWr) and Prof. Helena Hercman and Prof. Michał Gąsiorowski from the Institute of Geological Sciences, Polish Academy of Sciences.
The research was funded from the NCN MINIATURE project: Analysis of deformed speleothems from the Niedźwiedzia Cave in Kletno as a tool for palaeoseismic studies
Szczygieł, J., Sobczyk, A., Hercman, H., Mendecki, M. J., & Gąsiorowski, M. (2021). Damaged Speleothems and Collapsed Karst Chambers Indicate Paleoseismicity of the NE Bohemian Massif (Niedźwiedzia Cave, Poland). Tectonics, 40(3), e2020TC006459. https://doi.org/10.1029/2020tc006459
Sobczyk, A., & Szczygieł, J. (2021). Paleostress reconstruction of faults recorded in the Niedźwiedzia Cave ( Sudetes ): insights into Alpine intraplate tectonic of NE Bohemian Massif. International Journal of Earth Sciences, 0123456789. https://doi.org/10.1007/s00531-021-01994-1