Post-LGM faulting in Central Europe: LiDAR detection of the >50 km-long Sub-Tatra fault, Western Carpathians

Abstract

The increasing availability of high-resolution LiDAR data reveals surprisingly strong topographic evidence of late Quaternary faulting in some intraplate regions characterized by weak recent tectonic activity. For the first time, we present evidence of a >50 km-long post-Last Glacial Maximum (LGM) tectonic rupture along the southern margin of the Tatra Mountains (Slovakia) in the highest part of the Carpathian Mountains. Using a high-resolution 1 × 1 m LiDAR DEM, we recognize that the normal, range-bounding Sub-Tatra fault (STF) and its eastward branch, the Ružbachy fault (RBF), offset late Quaternary glacial moraines, alluvial fans and colluvial slopes. The fault zone morphology is dominated by a nearly continuous, southward-facing, up to ~18 m-high main scarp locally accompanied by antithetic fault scarps and hanging wall grabens. Similar offsets of pre-LGM and LGM deposits and the absence of fault scarps within Holocene alluvium suggest that the STF and RBF were active for a relatively short time interval between ~18 ka and the Holocene. Using the vertical separation of dated LGM moraine crests, we estimate that the minimum average postglacial slip rates along the STF and RBF varied from ~0.1–0.3 mm/year, i.e., rates one order of magnitude higher than those reported for other faults in Central Europe. Additionally, deep-seated landslides and the presence of large rock avalanches along the fault suggest possible postglacial high-magnitude earthquake(s) producing coseismic rupture of the STF and RBF. We conclude that 1) southern range-bounding faults of the Tatra Mountains are the longest (>50 km) and only documented post-LGM ruptures revealing extensive offset of late Quaternary deposits in the Western Carpathians and 2) relatively small along-strike variations in postglacial offset mimic the long-term exhumation trends and imply “en block” uplift of the southern margin of the Tatra Mountains with the highest displacement along the east STF.