which one is not a natural disaster

Bhopal gas tragedy is a man-made disaster. A human disaster is a disaster that is caused by man. But earthquakes, tsunamis, and volcano eruptions are all-natural disasters. We cannot hold anyone responsible for natural calamities, but human disaster arises due to human mistakes, which is likely to cause massacres on a large scale. Due to the efforts of man for development, many times such incidents happen which have a deep and terrible effect on the human life of the environment