Seismic noise: unfortunate companion of seismic measurements but also a scout from the Earth's depths

Seismic records are contamined by noise. In classical approach elastic waves generated by an earthquake or a quary blast are considered as a deterministic signal and seismic noise as a random signal. Commonly noise is removed or at least reduced by filtering. In recent years also an opposite approach appeared. Propagation of noise followed the same principles as for the deterministic signals - it is medium dependent