With gravity measurements in the tunnel and on the surface along the tunnel, our study assessed the geological model of the Gotthard Base Tunnel, the currently longest tunnel in the world (57.1 km). It turns out that local and regional rock-density data explain the structure very well. Full details in our publication in Swiss Journal of Geosciences.
Following years of development, testing and validation, our new approach how to construct a crustal structure and shear-wave velocity model based on seismic receiver functions has just been published. The first part of the paper explains the methodology, the second applies it to the Central Alps and the AlpArray dataset. One key element is the new model parameterization, shown below.