Moho map and receiver functions database beneath the European Alps using data from recent large-scale passive experiments

The Alpine orogen is a unique geological formation with a highly variable crustal structure. Despite numerous active and passive seismic investigations in the past, constraints on the crustal structure across the whole Alpine domain are still limited. To improve on this, we use waveform data from four past and ongoing large-scale passive experiments in the broader Alpine region: namely the AlpArray Seismic Network (AASN), which also includes many permanent stations in its footprint, the Eastern Alpine Seismic Investigation (EASI), the China-Italy-France Alps seismic transect (CIFALPS-1) and the Pannonian-Carpathian-Alpine Seismic Experiment (PACASE). This results in a composite seismic network of more than 700 broadband seismic stations, providing unprecedented data coverage.  

We apply a systematic processing workflow to these data and calculate Receiver Functions (RF). After applying strict quality control we obtained 107,633 high-quality RF traces, on average of 122 per station. Next, we developed codes to perform time-to-depth migration in a newly implemented 3D spherical coordinate system using a reference P and S wave velocity model. Finally, we compiled a new detailed Moho map by manually picking the depth of the discontinuity. Our Moho depth estimates generally support the results of previous studies in the region and vary from ca. 20 to ca. 55 km depth with the maximum values observed beneath the Alpine orogen. The RF dataset along with the codes and new Moho map are all open-access. 

The high quality and homogeneously calculated RF dataset, along with the new, coherently derived Moho depth map of the Alpine region, can provide helpful information for interdisciplinary imaging and modeling studies investigating the geodynamics of the European Alps orogen and its forelands (e.g., joint inversions with other geophysical and geological datasets).