A brief tutorial on how to load seismofaults.eu data on QGIS using OGC Web Map Service
Edit the Name field naming it freely and paste the GetCapabilities url from your clipboard in the URL field
This is a one time procedure since, as you click on OK the connection will remain in the configuration of QGis for future use.
Clicking Connect the list of the layers published by the server as WMS will be loaded and shown as following
EDSF: The entire EDSF dataset;
EDSF.Crustal_Fault_Sources: The two layers related to Crustal Faults (i.e. Planes and Top);
EDSF.Subduction_Zones: The two layers related to Subductions (i.e. zones and contour lines).
Take it into account since querying the combinated ones may lead to unexpected results.