High-resolution calibration of seismically-induced lacustrine deposits with historical earthquake data in the Eastern Alps (Carinthia, Austria)

Lake sediments are increasingly used to reconstruct recurrence intervals of large earthquakes - a prerequisite for the establishment accurate seismic hazard models because they can record strong shaking as mass-transport deposits (MTDs), turbidites or sediment deformations and often reach back several thousands years. To derive quantitative information on paleo-earthquake size, sedimentary imprints need be thoroughly calibrated with independent strength. A few calibration studies proposed scaling relationships between strength historical type size lacustrine imprints. Due incomprehensive mapping an insufficient documented earthquakes, however, rigorous testing these is lacking. Here, we study infill past ?800 years in Wörthersee Millstättersee, two lakes Eastern Alps (Carinthia, Austria). These have experienced five well-documented local intensities ranging from V – IX (EMS-98 scale). We trace signatures (MTDs turbidites) based vast dataset multibeam bathymetry, reflection profiles numerous precisely dated cores. Seismic low V½ recorded originating deltaic slopes, while hemipelagic slopes fail VI onwards. In Wörthersee, earthquake-recording thresholds highly dependent specific core locations due variations slope characteristics (composition, length, gradient) transport distance site. This highlights potential establishing multi-threshold paleoseismic records multiple coring sites single basin. both lakes, exponential size-scaling inferred intensity i) number volume ii) cumulative thickness turbidites. Moreover, relative turbidite presence increases linearly intensity, confirming results previous Chilean lakes. Application obtained first major earthquake Austria (1201 CE) suggests magnitude ?6.4 epicentre close Millstätter See. demonstrates that lake paleoseismology powerful tool obtain distribution paleo-earthquakes.