A column of three vibrating trucks is slowly driving through southern Limburg these weeks to map the structure of the subsurface in preparation for the possible construction of the Einstein Telescope under the hill country.
The heavy white trucks have a vibration plate between their four wheels that they can lower to the ground when stationary. The plate then vibrates in increasing frequency up to 100 vibrations per second, sending vibrational waves into the ground. Sensors are placed in the landscape every 10 meters that pick up vibrations reflected from underground structures.
The measurements enable a detailed picture to be made of the structure of the subsurface. That information is important in preparations for the Einstein Telescope, the underground detector for gravitational waves that could potentially be built in the area.
The Einstein Telescope (ET) is a proposed measuring instrument that can capture vibrations from space itself that reach Earth from the universe. These vibrations are created by colliding black holes and neutron stars and offer a whole new window into the cosmos.
The ET project is supported by the Province of South Limburg and foreign partners and technically prepared under the leadership of Nikhef. Earlier this year, the National Growth Fund awarded money for proposal preparation, plus a reservation for possible construction.
ET is planned to be a 10-kilometer-long triangle of tunnels in which sensitive laser arrays will be placed. The whole thing will be about 100 meters underground, to minimize disturbing vibrations from the environment. The Limburg soil seems potentially very suitable for the telescope because it is hard, but covered with a cushioning soft layer of sandstone.
The current vibration study should better map this structure. The results of the measurements will play a role in deciding whether the Netherlands will indeed submit a proposal for the Einstein Telescope in the South Limburg border region in the coming years.
The explorations take into account the surroundings, by avoiding villages or badger hills.
(Source: Province of South Limburg)