Moho and sub-Moho structure in the larger Alpine area from S-to-P conversions

Abstract

For the understanding of the fate of the lithosphere when continents are colliding, it is necessary to image the structures of the lithosphere. In the case of the Alps, the structure of the Moho is very well known. This is, however, not yet the case for the lower boundary of the lithosphere, the lithosphere-asthenosphere boundary (LAB). We are using S-to-P converted seismic waves to study the structures of the Moho and the LAB beneath the greater Alpine Area with data from the Alparray project and the European networks of permanent seismic stations. Besides a new European Moho map, we present more detailed information about negative velocity gradients (NVG) below the Moho which may be interpreted as LAB. We found the European mantle lithosphere is deepening from about 50°N below the Alps to the Apennines and Dinarides along the entire east-west extension of the Alps. This area has also an east dipping component towards the Pannonian Basin and the Bohemian Massif. In the East and West of this area the European mantle lithosphere is dipping towards the North. We also discuss possible source locations of the volcanoes of the European Cenozoic Rift System in the light of our data.