Natural disasters are those sudden events that usually are triggering widespread mass destruction, plenty of collateral loss, and damage to many lives. These events are considered to be brought by certain forces apart from the acts that are strictly associated with human beings, but they can also come as an effect of human actions.
A natural disaster usually is caused by earthquakes, volcanic eruptions, flooding, landslide, hurricanes, and so on. The planet has an uncontrollable state of flux, but its tremendous stresses might cause serious effects.
For example, while most events usually take place without any perceptible effects, there are some that might create serious havoc on humans and their properties. These are the worst natural disasters of the 21st century: