SHmax orientation in the Alpine region from observations of stress-induced anisotropy of nonlinear elasticity

SUMMARY The orientation of SHmax is commonly estimated from in situ borehole breakouts and earthquake focal mechanisms. Borehole measurements are expensive, therefore sparse, can only be made regions with many well-characterized earthquakes. Here, we derive the stress-field using stress-induced anisotropy nonlinear elasticity. In this method, measure strain derivative velocity as a function azimuth. We use natural pump-probe (NPP) approach which consists measuring elastic wave speed empirical Green’s functions (probe) at different points earth tidal cycle (pump). validated larger data set Northern Alpine Foreland region where maximum horizontal compressive stress known drilling-induced fractures. technique resolves NNW-SSW to N-S directed good agreement conventional methods recent crustal model. confirm that NPP method applied dense large-scale seismic arrays. then Southern Alps understand contemporary pattern associated ongoing deformation due counterclockwise rotation Adriatic plate respect European plate. Our results explain why two major faults Northeastern Italy, Giudicarie Fault Periadriatic Line (Pustertal–Gailtal Fault) currently inactive, while acting field allows Slovenia deform actively. have demonstrated has potential fill measurement gap left by approaches, both terms regional coverage depth.