Assessing seismically active faults is challenging in regions with low deformation rates. As slip rates are low and earthquake recurrence intervals are long, earthquakes may be absent in instrumental or historical seismic records. Adding to this problem, in glaciated regions such as the Eastern Alps, fault scarps and displaced sediments are often erased or buried, limiting classical paleoseismology. As a result, major faults like the Periadriatic Fault (PAF) System remain seismically ambiguous despite their long-lived geological history accommodating part of the ongoing Adria–Europe convergence. This thesis addresses that gap by applying electron spin resonance (ESR) and optically stimulated luminescence (OSL) dating to fault gouges from the PAF, the Lavanttal Fault, and the Šoštanj Fault. The methods date the accumulation of radiation-induced electrons stored in traps and released by shear heating during surface-rupturing earthquakes, bridging timescales between instrumental and long-term geological records. Methodologically, the thesis evaluates ESR measurement protocols, and introduces the combination of ESR (quartz, Al center) and OSL (K-feldspar) dating to constrain the time span of past surface-rupturing earthquakes by exploiting their different saturation limits. Results reveal contrasting behaviors: very limited Quaternary seismic activity along the Lavanttal Fault, Pleistocene activity along the PAF, and potentially higher activity at the Šoštanj Fault. As a final step, thermal de-trapping numerical models are adapted to ESR. By linking signal saturation to shear heating temperature, duration, and recurrence interval, the models provide quantitative constraints on earthquake frequency and suggest that short recurrence intervals are unlikely for the eastern PAF system. Overall, the thesis demonstrates that ESR and OSL dating offer a powerful framework for reconstructing seismic histories, and aid in improving long-term seismic hazard assessment.
Erick Prince (Wed,) studied this question.