Characterization of the seismic field at Virgo and improved estimates of Newtonian-noise suppression by recesses

A. Singha*, S. Hild, J. Harms, M.C. Tringali, I. Fiori, F. Paoletti, T. Bulik, B. Idzkowski, A. Bertolini, E. Calloni, R. De Rosa, L. Errico, A. Gennai

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review


Fluctuations of gravitational forces cause so-called Newtonian noise (NN) in gravitational-wave detectors which is expected to limit their low-frequency sensitivity in upcoming observing runs. Seismic NN is produced by seismic waves passing near a detector's suspended test masses. It is predicted to be the strongest contribution to NN. Modeling this contribution accurately is a major challenge. Arrays of seismometers were deployed at the Virgo site to characterize the seismic field near the four test masses. In this paper, we present results of a spectral analysis of the array data from one of Virgo's end buildings to identify dominant modes of the seismic field. Some of the modes can be associated with known seismic sources. Analyzing the modes over a range of frequencies, we provide a dispersion curve of Rayleigh waves. We find that the Rayleigh speed in the NN frequency band 10-20 Hz is very low (less than or similar to 100 m s(-1)), which has important consequences for Virgo's seismic NN. Using the new speed estimate, we find that the recess formed under the suspended test masses by a basement level at the end buildings leads to a 10 fold reduction of seismic NN.
Original languageEnglish
Article number245007
Number of pages13
JournalClassical and Quantum Gravity
Issue number24
Publication statusPublished - 16 Dec 2021


  • Newtonian noise
  • Rayleigh waves
  • recess
  • velocity dispersion

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