Geomorphological evidence of tectonic activity of the Marianske Lazne Fault (Czech Republic) and its influence to stream network evolution

Abstract

The Mariánské Lázně Fault (western Bohemia, CZE) is a morphologically, geologically and tectonically prominent structure with that is 150 km long with an NNW-SSE orientation. Its tectonic activity, especially in the NW part and in the neighbouring Cheb basin, is well known and has been proven by present-day earthquake swarms, mantle-derived CO2 emanations, geophysical and paleoseismological research. It seems that other parts of the MLF (especially segments of NNW-SSE and N-S orientation) might also have been active during the Pleistocene, possible even in the Holocene. This study provides a robust set of morphometric analyses – mountain-front sinuosity, basin asymmetry, longitudinal stream profiles, SL-index, which assesses the possibility of recent tectonic activity. The results suggest that the activity of the central and southern part of the MLF could have been very young. A reconstruction of the evolution of the stream network of the Mže River, as a result of different timing of the activity of particular segments of the MLF, is also put forward. The first ideas about the evolution of terrain morphology and the stream network are proposed by this study, however subsequent field research (geophysics, paleoseismology) could prove and date the tectonic activity. The delineation of segments with young activity may also have a great implication for seismic hazard assessment.