Seismic noise subsoil in order to draw seismic microzonation maps showing the predicted ground response to earthquakes. Research on the origin of seismic noise indicates that the low frequency part of the spectrum (below 1 Hz) is due to natural causes, chiefly ocean waves. In particular the peak between 0.1 and 0.3 Hz is clearly associated with the interaction of water waves of nearly equal frequencies but opposite directions. At high frequency (above 1 Hz), seismic noise is mainly produced by human activities such as road traffic and industrial work; but there are also natural sources, like rivers. Around 1 Hz, wind
Natural beech wood global climate changes can also have a profound effect on what kind of natural woodland can grow and survive in a specific area. European beech is usually more susceptible to climatic changes than soil-composition and the current global climate change are found to affect the geographical distribution of natural beech wood habitats. The term "Natural" is often confusingly used as a synonym for "Primeval". While primeval woodlands that still exists, are indeed natural, natural woodlands does not have to be primeval per se. Secondary or re-established woodlands can also be natural; it is just a matter of whether a given