Properties of seismic noise at the Virgo site

We present the results of a study of the major low-frequency sources of seismic activity at the Virgo site. These sources are of natural and human origin: oceanic microseism (below 1 Hz), local traffic and human activity on site (below 10 Hz). Using data collected during the commissioning of the central Virgo interferometer (CITF) we have measured the seismic coupling to the interferometer, demonstrating that seismic noise contributed to the CITF dark fringe noise only below approximately 2 Hz.