Definition
Natural disaster is a natural event that causes misery, damage, loss, and suffering of the population. Excluding catastrophe caused by plant pests or outbreaks. Other disasters such as hurricanes and so on. Noted that natural disasters
disasters that occurred in the last 3 years. Calculated based upon a number of disastrous episode.
Episode is a series of timed events that are not always coherent and interspersed with stops.
Example: a volcano during the last 2 months is always emits smoke and often erupt. For this kind of case we count 1 times 1 times the mountain erupted and smoke / fog.