Chairperson : Jo van den Brand

The main activity of the first work package is the definition of the site requirements and the proposition of possible sites in Europe. The specifications seem to be fulfilled by an underground site, where the low seismic activity and the uniformity of the soil may play a dominant role in the site identification process. This requires the study and the design of a complex underground international facility that features multi-kilometers tunnels to host the interferometer arms and cryogenic plants, while guaranteeing the safety of the infrastructure users. The site-selection studies encompass measurements of seismic activity (short- and long term) at candidate sites, collaboration with geophysicists and finite-element modeling. Furthermore, it is important to quantify the various contributions and identify approaches to limiting gravity gradient noise such as active correction systems by using data from seismic sensors. The study will identify the criteria for site selection and evaluation. These include: site availability and acquisition risk, scientific suitability, construction suitability and operations suitability. In addition, there are issues related to acquisition of land rights, importance of different noise sources, site dependent construction costs due to topographic variation, geological and environmental considerations, flood control, distance to nearby supporting technical facilities, university support, operating costs, surrounding communities providing accommodations for permanent and visiting staff, availability of local skilled work force, accessibility and travel time for visiting staff, environmental dangers from earthquakes, storms, flooding, legal issues, etc. Finally, the definition of the requirements for buildings and tunnels will be addressed. For the latter it is important to discuss the merit of the proposed solutions for tunnels and buildings, safety systems, and cost models with experts in the field.