GFZ German Research Centre for Geosciences, Potsdam, Germany
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.
How to cite. Spooner, C., Scheck-Wenderoth, M., Cacace, M., and Anikiev, D.: How Alpine seismicity relates to lithospheric strength, Solid Earth Discuss. [preprint], https://doi.org/10.5194/se-2020-202, 2020.
Received: 30 Nov 2020 – Discussion started: 09 Dec 2020
By comparing long term lithospheric strength to seismicity patterns across the Alpine region, we show that most seismicity occurs where strengths are highest within the crust. The lower crust appears largely aseismic due to energy being dissipated by ongoing creep from low viscosities. Lithospheric structure appears to exert a primary control on seismicity distribution, with both forelands display a different distribution patterns, likely reflecting their different tectonic settings.
By comparing long term lithospheric strength to seismicity patterns across the Alpine region, we...