This project is designed to collect and provide seismological data through a dense seismological network in the central and eastern Alps. The 154 densely spaced stations planned here will complement the larger-scale AlpArray Network ("backbone"). SWATH D focuses on a key region of the Alps where the polarity of the subduction may change and where TRANSALP found a jump in the Moho. The data generated in this project are required by 15 individual applications in the SPP; 15 other proposals need products (e.g. tomographic images) resulting therefrom. SWATH D is therefore an important part within the SPP and the international AlpArray community, as well as a scientific service for the majority of the projects in the SPP.