Neotectonics of the Eastern Alps investigated in caves

Numerous field studies, seismic data, and GPS observations suggest ongoing activity along major tectonic fault systems in the Eastern Alps. However, discrete geological proofs characterizing the recent activity of individual fault systems are rather scarce. As tectonically damaged speleothems and micro-displacement measurements in karst caves have proven to provide unique quantitative information on neotectonic activity, this study aims on providing the first comprehensive and detailed assessment of Quaternary tectonic activity and recent dynamics of micro-displacements along major fault systems of the Eastern Alps registered in caves. In the first step, traces of active faults in caves will be documented on the basis of field observations, literature research and by checking hints from the speleological community. Cave passages that have been dislocated by active faulting and which are coated by flowstone that grew before as well as after the tectonic event will be dated by the U- series disequilibrium method for achieving the age of respective neotectonic events. In order to reconstruct the local stress conditions during the (re)activation of the faults, the paleostress field will be, if possible, calculated from fault-slip data of the recent dislocations. In order to discriminate between fault displacements caused by seismic slip or aseismic creep, which is an essential task for identifying paleo-earthquakes, micro-tectonic studies of faulted flowstones using cathodoluminescence images with electron backscattered diffraction will be the basic methods. At selected prominent test sites, recent dynamics of micro-displacements along single faults that are related to major fault systems will be monitored by means of the high-accuracy 3D crack-gauge TM71. The potentially recorded micro-displacements will be correlated with regional seismic activity in the study area of the Eastern Alps in Austria and with other influencing factors. Finally the obtained data are a solid base for updating the paleoseismic record of the Eastern Alps for regional earthquake hazard assessment.

No additional funding sources recorded.