MAASTRICHT. An American study has shown that the earth under the German Eifel mountain range, to the south of Aachen, moves and rises by one millimetre per year. Does that have any consequences for the Maastricht research into gravitational waves? And hence also for the possible arrival of the hypersensitive Einstein Telescope?
“Something is brewing under the centre of North-West Europe,” said one of the researchers recently to Dagblad De Limburger newspaper. The earth movements in the triangle Aachen, Trier and Koblenz appear to be more powerful than was expected and according to earth scientists they reach as far as Luxembourg, Eastern Belgium and Limburg.
The question is, whether these movements below the surface are able to disturb the detection of gravitational waves? At the moment, the UM is building a test set-up - ETpathfinder - in the ‘black box’ on the Duboisdomein, and the provincial council is hoping that South Limburg (rather than Sardinia) will be get the brand new gravitational wave detector: the Einstein Telescope, in 2024 – the site decision is delayed because of the corona crisis.
According to Stefan Hild, the Maastricht professor in the field of research into gravitational waves, the underground activity in the Eifel will not affect the local plans. Before South Limburg put itself forward as a suitable location for the Einstein Telescope, seismic soil research started, he said. “Since a year we are measuring the seismic activity with a sensor placed 250 meter underground and we have so far not seen any extra noise related to the Eifel rising.”
Besides, a rise of 1 millimetre per year is a very slow process and will happen at very low frequencies and far away from the site of the Einstein Telescope, says Hild. “It is hard to see, even when it comes to the durability of the underground infrastructure, how 1millimetre per year could cause any trouble.”
The Einstein Telescope forms of a kilometres-long, triangular installation, hundreds of metres underground. “As long as the tunnels and the corners of the triangle move in the same way, and this is what the America study suggests, the only effect will be that after fifty years of operation, the telescope would have moved five centimetres further away from the center of the earth. This will make no difference for the detection of gravitational waves.”