Damaged Speleothems and Collapsed Karst Chambers Indicate Paleoseismicity of the NE Bohemian Massif (Niedźwiedzia Cave, Poland)

Abstract

A moment magnitude greater than M6.5 is needed to express a fault in topography (McCalpin & Nelson, 1996), and secondary effects such as landslides or liquefaction M > 5 are inevitable (Ambraseys, 1988; Keefer, 1984). Little or nothing remains in the geological record after a lower magnitude event, especially when both the morphology and deposits are remodeled by ice sheets or periglacial processes, as is the case in a majority of the Northern Hemisphere. In a tectonically stable part of Europe, despite the European Cenozoic Rift System (ECRS) crossing eastward from the Carpathians and westward from the North Sea (Špaček et al., 2015; Ziegler, 1992), singular events strong enough to produce fault ruptures have been recorded (e.g., Camelbeeck & Meghraoui, 1998; Štěpančíková et al., 2010, 2019). A prominent example of the tectonic structure of the ECRS is one of the most significant tectonic lines in Central Europe-the Sudetic Marginal Fault (SMF), which is approximately 200 km long. The NW-SE-trending fault bounds the Bohemian Massif to the north, as expressed by the 130-km long morphological step. Historical earthquakes along the SMF were not high intensities (I < 7 on the EMS intensity scale; Guterch, 2015). The minimum moment magnitude of prehistoric earthquakes has been estimated to be M6.3 (Štěpančíková et al., 2010), which theoretically can produce higher intensity earthquakes (I∼8.8 in the epicenter on the MSK intensity scale). According to the earthquake hazard map for Czechia, Poland, and Slovakia (Schenk et al., 2001), the Sudetes region's intensity should not exceed I = 6.5 (MSK). This reveals two issues: (1) earthquakes in the Sudetes region occurred in historic and prehistoric times, and (2) their intensities might not have been strong enough to have produced earthquake effects that were preservable in the geological record, especially since the landscape was remodeled by glacial and periglacial processes. However, cave environments are separated from external erosive factors and often favor preserving traces of past processes and events, after which marks on the surface are obliterated or covered.

Collapse wedges in periglacial eolian sands imply Late Pleistocene paleoseismic activity of the Vienna Basin Transfer Fault (western Slovakia)

“…Paleoseismological research focusing on the intensity and recurrence intervals of earthquakes through geological time is of primary importance in the prediction of geohazards related to seismic events. The direct determination of fault activity is routinely carried out for example through the exposure dating of fault scarps (Benedetti et al, 2003;Palumbo et al, 2004;Carcaillet et al, 2008;Tikhomirov et al, 2014), by the dating of successive events using disrupted sediment layers in trenches (Enzel et al, 2000;Decker et al, 2005;Štěpančíková et al, 2008;Štěpančíková et al, 2010;Le Dortz et al, 2011;Hintersberger, 2012;Ansberque et al, 2016;Weissl et al, 2017;Hintersberger et al, 2018), or by dating the deformation of sinters in caves (Plan et al, 2010;Gribovszki et al, 2017;Szczygieł et al, 2021). Significant attention has also been paid to the seismically triggered deformation of sediments related to liquefaction (Guarnieri et al, 2009;Moernaut et al, 2009;Alessio et al, 2012;Holzer et al, 2015;Amorosi et al, 2016).…”

Paleostress reconstruction of faults recorded in the Niedźwiedzia Cave (Sudetes): insights into Alpine intraplate tectonic of NE Bohemian Massif

“…In fact, the age of Niedźwiedzia Cave origin is rather poorly constrained, with only scarce constraints on speleothems formation dating back the onset of this process to late Middle Pleistocene (ca. 300-350 ka; Szczygieł et al 2021), but not further. Accordingly, the available geochronological record provides only a rough approximation for a minimum age for local water table drop and the onset of valley incision.…”

Problem sztuki naskalnej w Polsce

“…Zlodowacenie wpływało na klimat, a co się z tym wiąże, na szybszą degradację przedstawień, jak i na wzmożoną erozję nacieków jaskiniowych, być może zdobionych sztuką naskalną. Ponadto do niszczenia nacieków jaskiniowych dochodziło także podczas trzęsień ziemi, czego przykładem jest Jaskinia Niedźwiedzia (Szczygieł, Sobczyk, Hercman, Mendecki, Gąsiorowski, 2021). Destrukcyjny wpływ na ryciny i malowidła jaskiniowe ma również powstawanie i przyrastanie nacieków krasowych.…”