Vehicle-induced seismic effects at a gravitational wave observatory

The seismic signature of a vehicle traveling on the site of the Australian International Gravitational Observatory has been studied using a two-axis seismometer. The main laboratory strongly attenuated the vehicle-induced seismic noise across all frequencies. We find that the magnitude of the vehicle-induced seismic signal followed a d−γ power law, with d the source–detector distance and γ≈1.7±0.4. The results are indicative of strong attenuation of seismic disturbances and are consistent with other measurements of low-amplitude Rayleigh wave attenuation in similar sandy soil types, a highly desirable property for the site of a gravitational wave observatory. This analysis provides a tool for estimating the magnitude of vehicle-induced seismic noise at the laboratory buildings from more distant sources on and around the site.