In the disaster management cycle impact refers to the point at which a hazard event occurs; for instance, when a cyclone or an earthquake strikes a particular area. Its inclusion serves as a reminder that, in disaster management terms, the impact can vary depending on the nature of hazard.
An earthquake generally strikes without any warning, and its impact time is very short. Yet the impact, particularly in case of high magnitude earthquakes, is generally very severe.
Contrary to this with the advancement in satellite remote sensing techniques it has been possible to generate cyclone warnings with long lead time, and its impact time can be protracted. This maybe particularly so if the cyclone passes directly over a given area, or back-tracks as may sometimes occur.
Prior assessment of the impact time provides opportunity of putting in place various mitigation measures that include warning dissemination, evacuation, deployment of search and rescue teams, activation of emergency support functions and the like, so as to minimise human casualities and loss of property and assets.