Quantitative paleoseismology in Carinthia, Eastern Alps: Calibrating the lacustrine sedimentary record with historical earthquake data

• DOI: 10.5194/egusphere-egu2020-10802
• Publication Date: 2020-03-09T21:42:26Z
• Authors: Christoph Daxer; Christa Hammerl; Maria del Puy Pap...; Stefano Claudio F...; Patrick Oswald; Jyh-Jaan Steven H...; Michael Strasser; Jasper Moernaut
• Keywords: Paleoseismology

<p>In intraplate settings with moderate seismicity, recurrence intervals of strong earthquakes (M<sub>w </sub>>6) typically exceed the short time span instrumental and historical records. To assess seismic hazard in such regions, lake sediments are increasingly used as earthquake archives: they can record shaking mass transport deposits (MTDs), turbidites or sediment deformations, preserved over several thousands years. provide information on paleo-earthquake size, however, sedimentary imprints need to be thoroughly calibrated independent strength.</p><p>In Carinthia (Eastern Alps, Austria), numerous lakes have experienced devastating local intensities (SI) ranging from V-XI (EMS-98 scale), although being located an environment. Given that i) these events well-spaced (AD1201, AD1348, AD1511, AD1690, AD1857 AD1976), ii) due research, exceptional documentation exists, iii) accurate shakemaps built based a Intensity Prediction Equation (IPE), we examine relationship between intensity type, size spatial distribution imprint lakes.</p><p>Here, present investigations two large – Wörthersee Millstätter See by dense grid reflection profiles (~640 km overall), 80 (~1.5 m) cores multibeam bathymetry. The consist sub-basins potentially different thresholds for generation imprints. Mapping MTDs, their scarps associated well dating (radiocarbon varve counting thin sections) shows AD1348 (M<sub>w</sub> ~7) led extensive slope failures both lakes. AD1511 ~6.9) AD1690 ~6.5) events, which exhibited lower (~VII) compared those (VIII), recorded minor MTDs turbidites. Quantitative description earthquake-related event (cumulative turbidite thickness, volume deposits/megaturbidites) suggests linear correlation respective See.</p><p>The AD1976 ~6.5; SI V-VI at lakes) is not evidenced therefore constraining minimum threshold seismically-induced deposits. By applying grid-search approach using empirical intensity-attenuation relationship, narrow down possible scenarios. Our data highly debated epicentre was much closer Austrian-Italian border than Friuli earthquake, possibly originating Periadriatic lineament. probably had its southeast our study area Slovenia, further east previous studies suggested. most likely origin.</p><p>Our reveals investigating one lake, let alone core, insufficient reconstruct region’s history. Due setting Carinthia, constrain pattern localise epicentral region fault source past earthquakes. In ongoing interdisciplinary study, use this calibration construct long lacustrine records last 14 ka.</p>