LIAG-Seminar: Identifying fossil fault activity along the eastern Periadriatic Fault system by combined OSL- and ESR-dating of fault gouge

Programm

Erick Prince: Identifying fossil fault activity along the eastern Periadriatic Fault system by combined OSL- and ESR-dating of fault gouge

Abstract:

Faults in slowly deforming regions, such as the Eastern Alps, accumulate strain over long timescales and produce only rare large earthquakes, often missing from instrumental and historical records. Pleistocene glaciations further obscure evidence by eroding or burying fault features, limiting traditional paleoseismology. The Periadriatic Fault (PAF), a major fault in the European Alps, had a main onset of activity during the Oligocene–Miocene and has since slowed, leaving its present-day seismic potential debated. To investigate its Quaternary seismic activity, we applied electron spin resonance (ESR) and optically stimulated luminescence (OSL) dating of fault gouges. These methods are sensitive to shear heating produced during earthquakes. Analyses carried out in gouges from the PAF, the Šoštanj Fault and the Lavanttal Fault reveal contrasting activity patterns, ranging from limited to recurrent seismic activity. Numerical modeling further suggests that earthquake recurrence on the PAF spans from tens of thousands to over a million years depending on the earthquake magnitude. These findings highlight the value of ESR and OSL dating, helping to bridge gaps between geological, historical, and instrumental seismological records in their respective timescales, and contribute to seismic hazard assessments.