Most natural disasters that occur frequently may be classified into four main categories: floods, earthquakes, cyclones and famine. Other catastrophic events, such as land slides, avalanches, snow storms, fires occur at rarer occasions and threaten smaller proportions of the populated world. The destructive agents in the above categories are wind, water (a lack or excess thereof) and tectonic force. While all of these cause structural damage, their mortality and morbidity effects are varied both between them and over time. The disaster cycle can be differentiated into five main phases, extending from one disaster to the next. The phases are: the warning phase indicating the possible occurrence of a catastrophe and the threat period during which the disaster is pending; the impact phase when the disaster strikes; the emergency phase when rescue, treatment and salvage activities commence; the rehabilitation phase when essential services are provided on a temporary basis; the reconstruction phase when a permanent return to normality is achieved. The disaster-induced mortality and morbidity differ between these phases and are also a function of the prevailing health and socioeconomic conditions of the affected community. As a result of this, global statistics on disasters seem to indicate a significantly higher frequency of natural disasters in the developing countries than in the industrialized world.
The Effects of Repetitive Drop Jumps on Impact Phase Joint Kinematics and Kinetics