The nature of a society is altered by its ecology and environment. Modern technology has significantly altered the impact of environment on society. However, catastrophic events that take place can change the structure of a society completely. For instance, the tsunami that occurred in the Indian Ocean changed the lives of people drastically. These changes are irreversible and permanent in nature. There was a great loss of lives, loss of livelihood and in many cases, large scale migration of people to new areas in search of new opportunities. Thus, the tsunami became an agent of social change. Similar phenomena are associated with floods, draughts and earthquakes.