Speaker
Description
Newtonian noise arising from seismic density perturbations is expected
to limit the low-frequency sensitivity of third-generation gravitational-wave detectors such as the Einstein Telescope. Analytical predictions of Newtonian noise typically rely on homogeneous half-space or full-space approximations and simplified assumptions about seismic wavefields, which are insufficient for realistic site-specific modeling in layered geological media. We present a numerical framework for computing Newtonian noise in arbitrarily layered one-dimensional Earth models. The method combines frequency-domain Green’s functions computed with QSEIS for layered media with stochastic synthesis of seismic displacement fields generated by vertical and horizontal
surface forces. The implementation is validated against
analytical results for homogeneous half-space Rayleigh waves and isotropic full-space body-wave fields. Unlike traditional methods which solves for the wavefield using a wave-equation solver, we present a fast solver which leverages the axisymmetric properties of the propagation medium to compute the displacement field and hence the resulting Newtonian noise. The framework is also applied to a representative layered geological model relevant to Einstein Telescope site studies and quantify deviations from homogeneous predictions. Our results show that realistic stratification can significantly modify seismic correlations and the resulting Newtonian noise spectrum, underscoring the importance of layered modeling for next-generation gravitational-wave observatories.