Seismic topographic scattering in the context of GW detector site selection

TL;DR

This study calculates seismic scattering caused by surface topography to evaluate its impact on Newtonian-noise in site selection for future gravitational-wave detectors, highlighting the importance of topography in site suitability.

Contribution

It introduces a method to assess seismic topographic scattering across US sites, emphasizing its role in gravitational-wave detector site selection.

Findings

Flat sites like Oregon show minimal scattering impact.

Montana site exhibits significant wave broadening due to topography.

Topographic scattering should be considered in site selection criteria.

Abstract

In this paper, we present a calculation of seismic scattering from irregular surface topography in the Born approximation. Based on US-wide topographic data, we investigate topographic scattering at specific sites to demonstrate its impact on Newtonian-noise estimation and subtraction for future gravitational-wave detectors. We find that topographic scattering at a comparatively flat site in Oregon would not pose any problems, whereas scattering at a second site in Montana leads to significant broadening of wave amplitudes in wavenumber space that would make Newtonian-noise subtraction very challenging. Therefore, it is shown that topographic scattering should be included as criterion in the site-selection process of future low-frequency gravitational-wave detectors.