CBSE Class 11 — Notes, Chapters & Practice Quizzes

Chapter 6: Natural Hazards and Disasters

Summary

A disaster is an undesirable occurrence resulting from forces largely outside human control that strikes quickly and causes serious disruption of life and property. Natural hazards are elements of the natural environment with the potential to cause harm, while natural disasters are relatively sudden, widespread events causing large-scale loss. Disasters can be caused by natural forces or by human activities (directly, like the Bhopal Gas tragedy, or indirectly, like deforestation-induced floods). Natural disasters are classified as atmospheric, terrestrial, aquatic and biological. India, vast and diverse, experiences most of them. Earthquakes, the most unpredictable and destructive, result from the northward movement of the Indian plate against the Eurasian plate; India is divided into five earthquake-damage-risk zones. Tsunamis are seismic sea waves generated by sudden sea-floor movement, devastating coasts (as in December 2004). Tropical cyclones, energised by latent heat, strike the eastern and western coasts and cause storm surges. Floods, slow and well-identified, recur in Assam, West Bengal and Bihar, while droughts (meteorological, agricultural, hydrological and ecological) affect Rajasthan and central India. Landslides, controlled by localised factors, occur in the Himalayas and Western Ghats. Disaster management involves pre-disaster preparedness, during-disaster rescue and relief, and post-disaster rehabilitation, supported by the Disaster Management Bill, 2005. (Refer to the map in the NCERT textbook.)

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