First evidence of seismically-induced deformations in fluvial deposits of the Lower Rotliegend in the Intra-Sudetic Basin, SW Poland

The Lower Rotliegend in the Intra-Sudetic Basin, situated at the northern margin of the Bohemian Massif, is represented in the Polish part of the basin by the Krajanów and Słupiec formations. Both formations consist of fluvial and lacustrine deposits. The sedimentary processes during the deposition of the Słupiec Formation were influenced by volcanic activity that resulted in subvolcanic intrusions, lava flows and ignimbrites. Some slabs of fluvial sediments from the Słupiec Formation show a level consisting entirely of soft-sediment deformation structures, in particular load casts, sometimes representing successive phases of loading. These deformations are interpreted to record volcanism-related earthquakes. Also a level full of load casts in the fluvial part of the Słupiec Fm. can feasibly be explained only be earthquakes that must be ascribed to a volcanic eruption