Answer:
Most natural disasters are completely natural. These include earthquakes, volcanic eruptions, floods, severe storms, tornadoes, cyclones (including typhoons and hurricanes), hailstorms, droughts, blizzards and heatwaves.
Some natural disasters may be started by man. Man is a common cause of bushfires, for example, although bushfires can also be started by lightning strikes.
The effects of many natural disasters are often made worse by man's activities. Floods can be made worse by poor drainage. The effects of earthquakes are worse where man has not built sufficiently strong structures to withstand forces.