Natural disaster seismic waves. At the Earth's surface, earthquakes manifest themselves by vibration, shaking, and sometimes displacement of the ground. Earthquakes are caused by slippage within geological faults. The underground point of origin of the earthquake is called the "seismic focus". The point directly above the focus on the surface is called the "epicenter". Earthquakes by themselves rarely kill people or wildlife. It is usually the secondary events that they trigger such as building collapse, fires, tsunamis (seismic sea waves) and volcanoes. Many of these could possibly be avoided by better construction, safety systems, early warning and planning. When natural erosion, human
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