A disaster is the impact of a natural or human-made hazard that negatively affects society or environment. The word disaster's root is from astrology: this implies that when the stars are in a bad position a bad event will happen. Disasters occur when hazards strike in vulnerable areas. Hazards that occur in areas with low vulnerability do not result in a disaster; as is the case in uninhabited regions. It is often argued that all disasters are human-made, because human actions before the strike of the hazard can prevent it developing into a disaster. Hazards are routinely divided into natural or human-made, although complex disasters, where there is no single root cause, are more common in developing countries. A specific disaster may spawn a secondary disaster that increases the impact. A classic example is an earthquake that causes a tsunami, resulting in coastal flooding.