Physical Characterization of the Greater Alpine Crust as Inferred by Seismic Data

The Alpine orogen, together with the adjacent Apennines, Dinarides, their forelands, and surrounding sedimentary basins, represents one of the most studied regions on Earth. Many geological, geophysical, and geodynamic models that are now applied worldwide were first developed, tested, and validated in this area. Although it is one of the most intensively studied orogenic systems in the world, most existing geophysical models rely on isotropic seismic velocities and neglect anelastic and thermodynamic effects. Therefore, fundamental physical properties such as attenuation, temperature, composition, and anisotropy remain poorly constrained, limiting our ability to relate present-day seismic structures to their tectonic and geodynamic evolution. Recent advances in passive seismic imaging, particularly ambient noise interferometry and dense broadband networks, now make it possible to resolve these parameters at regional scale. In this thesis, we use the extensive publicly available seismic data from the greater Alpine region to conduct three complementary analyses: (i) an investigation of Rayleigh-wave attenuation in the Alpine crust using ambient noise, (ii) a study that combines seismic observables from ambient noise and receiver functions to perform thermodynamic modeling of the crust, and (iii) an analysis of the radial anisotropy of the crust and upper mantle based on Rayleigh and Love waves obtained from both ambient noise and earthquake data. Together, the estimates of attenuation, velocity, temperature, composition, and anisotropy across these studies allow us to understand how different physical properties jointly and independently explain the processes that develop from the upper mantle to the surface. We identify an anticorrelation between surface-wave velocity and attenuation, which enables us to evaluate the role of fluid-filled fractures in the dissipation of seismic energy and to infer their distribution within the crust. High attenuation in tectonically active areas indicates that fluid-filled fractures play a dominant role in the dissipation of seismic energy and that attenuation systematically decreases with increasing crustal age and tectonic quiescence. Quantifying variations in temperature and crustal composition enable us to distinguish a relatively colder, silica-rich Variscan crust from a hotter, more mafic Alpine–Apenninic crust, while also revealing systematic discrepancies between observed seismic velocities and those predicted by mineral-physics models. Finally, the radial anisotropy of the crust and upper mantle provides key evidence of collisional dynamics, allowing us to identify radial anisotropy patterns that serve as proxies for subsurface deformation and orogenic processes. Overall, these results demonstrate that the integration of complementary seismic observables provides a unified framework to relate physical properties to the tectonic and geodynamic evolution of the Alpine–Apennine–Dinaride system.