In 2009, the Swiss Seismological Service started a project to renew and extend its strong motion network (SSMNet). In the first phase of the project, 30 new stations have been installed until 2013, replacing old dial-up stations as well as instrumenting new sites. The second phase of the project started in 2014 and aims at installing another 70 stations by the end of 2019. The goals of the renewal project are an improved spatial coverage of regions with high seismic risk, a better localization capability of earthquakes in such areas and finally the verification and enhancement of seismic hazard models in Switzerland. All new stations are free-field stations. Most of them are built in densely populated urban areas with increased seismic risk, but also in areas where strong historical earthquakes took place.

All new installation sites are systematically characterized by passive and/or active seismic methods through the analysis of surface waves. Using one or several passive seismic arrays, we measure Love and Rayleigh wave dispersion curves using different methods, eg spatial autocorrelation (SPAC), 3-component high-resolution frequency-wavenumber analysis (3C-HRFK) and a maximum likelihood method (WaveDec). We further measure the Rayleigh wave ellipticity for the different stations of the array, as well as the polarization properties of the seismic wave field. For some sites with particular conditions (eg rock sites or lack of space), we also perform active measurements using the MASW and seismic refraction techniques.