In addition to killing and injuring people and causing extensive environmental, social, and economic damage, sudden-impact natural disasters often create an immediate obstacle to response by disrupting vital services (e.g. water, health, and security services) as well as key communication and transportation systems.

Sudden-impact natural disasters can be triggered by:

- cyclones, hurricanes, tornadoes;
- snowstorms;
- tsunamis (seismically induced waves);
- storm surges;
- flash floods;
- fires;
- earthquakes;
- landslides and avalanches; and
- volcanic eruptions.

The impact of any one of these hazards upon a vulnerable population can cause a disaster. Nonetheless, natural hazards occur in well-defined patterns. Susceptible areas can be rather easily identified, and therefore emergency plans should be prepared that outline administrative and technical responsibilities and procedures for a health response to all likely natural disasters. These plans should be multisectoral and linked to any other existing emergency plans.