Online map of China 's natural disaster - Integrated index

In the illustration, the comprehensive index from high to low is: 2.2-3.0；2.0-2.2；1.8-2.0；1.6-1.8；1.4-1.6；1.2-1.4；1.0-1.2；0.5-1.0；0.2-0.5.

Natural disasters are formed in different stages of time and urgency. Some natural disasters, when the change of disaster-causing factors exceeds a certain intensity, will behave as disaster behavior in a few days, hours or even minutes or seconds, such as volcanic eruptions, earthquakes, floods, hurricanes, storm surges, hailstorms, snow disasters, rainstorms and so on. Such disasters are called sudden natural disasters. Drought, diseases of crops and forests, insects and weeds, etc., generally occur within a few months, but the formation and end of disasters are still relatively rapid and obvious, so they are also included in sudden natural disasters. Under the condition of the long-term development of the cause of disasters, some natural disasters have emerged gradually factor, such as land desertification, soil erosion, environmental deterioration, etc. These disasters usually take several years or longer to develop, which is called slow-onset natural disasters.