Istituto Nazionale di Geofisica e Vulcanologia, Pisa, Italy
We present analyses of the noise wave field in the vicinityof Virgo, the Italian–French gravitational wave observatorylocated close to Pisa, Italy, with special reference to the vibrations induced by a nearby wind farm. The spectral contributionof the wind turbines is investigated using (1) onsite measurements,(2) correlation of spectral amplitudes with wind speed,(3) directional properties determined via multichannelmeasurements, and (4) attenuation of signal amplitude withdistance. Among the different spectral peaks thus discriminated,the one at frequency 1.7 Hz is associated with the greatest power, and under particular conditions it can be observed at distances as large as 11 km from the wind farm.
The spatialdecay of amplitudes exhibits a complicated pattern, which weinterpret in terms of the combination of direct surface wavesand body waves refracted at a deep (800 m) interface betweenthe Plio-Pleistocenic marine, fluvial, and lacustrine sedimentsand the Miocene carbonate basement. We develop a model for wave attenuation that allows determining the amplitude of the radiationfrom individual turbines, which is estimated on the order of for wind speeds over the8–14 m/s range. On the basis of this model, we then developa predictive relationship for assessing the possible impactof future wind farm projects.
Gilberto Saccorotti and Davide Piccinini
UCD School of Geological Sciences, University College Dublin, Belfield, Dublin 4, Ireland firstname.lastname@example.orgIrene Fiori European Gravitational Observatory, Via E. Amaldi 56021, S.Stefano a Macerata, Cascina (PI), Italy email@example.com
*Also at Istituto Nazionale di Geofisica e Vulcanologia, Pisa, Italy