How Alpine seismicity relates to lithospheric strength

Abstract. Despite the amount of research focused on the Alpine orogen, different hypotheses still exist regarding varying seismicity distribution patterns throughout the region. Previous measurement-constrained regional 3D models of lithospheric density distribution and thermal field facilitate the generation of an observation-based rheological model of the region. Long term lithospheric strength was then calculated and compared to observed seismicity patterns, showing that the highest strengths within the crust (~ 1 GPa) and upper mantle (> 2 GPa), occur at temperatures characteristic for specific phase transitions (crust: 200–400 °C; mantle: ~ 600  °C) with almost all seismicity occurring in in these regions. Correlation in the northern and southern forelands between crustal and lithospheric strengths and seismicity show different patterns of event distribution, reflecting their different tectonic settings. Seismicity in the plate boundary setting of the southern foreland corresponds to the integrated lithospheric strength, occurring mainly in the weaker domains surrounding the strong Adriatic indenter. However, in the intraplate setting of the northern foreland seismicity instead corresponds to the crustal strength, mainly occurring in the weaker and warmer crust beneath the URG. Results generated in this study are available for open access use to further discussions on the region.