Natural hazards are the naturally occurring events that can cause damage to life, property and the environment. When such a hazardous event actually occurs and causes significant loss, it becomes a natural disaster. India is highly vulnerable to natural hazards because of its location, physiography and climate. The Himalayan region is earthquake-prone and landslide-prone, the northern plains and eastern coasts face floods and cyclones, and parts of the peninsula are drought-prone.
The study of natural hazards and disasters is of great practical importance because disasters cause enormous loss of human life and property, disrupt economic activity and set back development. Understanding the causes, characteristics, distribution and management of natural hazards is essential for disaster preparedness, mitigation and response. In this chapter we study the major natural hazards of India, including earthquakes, floods, droughts, cyclones, tsunamis, landslides and volcanic eruptions, and the approach to disaster management.
A hazard is a threatening event or situation that has the potential to cause harm, while a disaster is the actual occurrence of such an event when it causes significant damage. Hazards are natural (earthquakes, floods) or human-induced (industrial accidents, terrorism). Natural hazards can be classified on the basis of their origin: 1. Geological hazards: Earthquakes, volcanic eruptions, landslides, tsunamis. 2. Water and climatic hazards: Floods, droughts, cyclones, tornadoes, heat waves and cold waves. 3. Biological hazards: Epidemics and pest attacks. Disasters are assessed by their frequency, magnitude and the vulnerability of the affected population.
An earthquake is the sudden shaking of the Earth's surface caused by the sudden release of energy in the Earth's crust, usually along faults. The energy release occurs mainly at plate boundaries. The point where the earthquake originates is the focus, and the point on the surface directly above it is the epicentre. India is highly earthquake-prone, especially the Himalayan region, which lies on the boundary between the Indian and Eurasian plates.
The whole Himalayan region, from Kashmir in the west to the north-eastern states, is a high-risk zone. The peninsular region was traditionally considered safe, but earthquakes have occurred in recent years in regions like Latur (1993), Bhuj (2001), and the 2004 earthquake that generated the Indian Ocean tsunami. The earthquake hazard map of India divides the country into zones from Zone V (highest risk) to Zone II (lowest risk).
Earthquakes cause ground shaking, building collapse, fires, landslides and tsunamis. Their effects can be reduced by earthquake-resistant construction, proper land-use planning, and awareness and preparedness. The National Disaster Management Authority (NDMA) coordinates earthquake preparedness in India.
A tsunami is a series of ocean waves caused by large-scale disturbances such as submarine earthquakes, volcanic eruptions or landslides. The word "tsunami" is Japanese, meaning harbour wave. Tsunamis travel at very high speeds in deep water and grow in height as they approach shallow coastal water.
The 2004 Indian Ocean tsunami, caused by a magnitude 9 earthquake off Sumatra, devastated the coastal areas of India (Tamil Nadu, Kerala, Andhra Pradesh and the Andaman and Nicobar Islands), Sri Lanka, Indonesia and Thailand. The Indian government established the Indian Tsunami Early Warning System at the Indian National Centre for Ocean Information Services (INCOIS) in Hyderabad to detect and warn of tsunamis.
Tropical cyclones are intense low pressure systems that form over warm tropical oceans with sea surface temperatures above 27 degrees Celsius. In India, cyclones form mainly in the Bay of Bengal and the Arabian Sea. The Bay of Bengal cyclones are more frequent because of the higher sea surface temperatures, higher salinity and the funnel-shaped coast.
Cyclones strike the eastern coast of India frequently, with a vulnerable zone stretching from West Bengal, Odisha, Andhra Pradesh and Tamil Nadu. The Odisha super cyclone of 1999 and Cyclone Phailin (2013) and Cyclone Fani (2019) caused massive destruction. Cyclones bring violent winds, torrential rain and storm surges (abnormal rise of sea level), which cause the maximum loss of life. India's National Cyclone Risk Mitigation Project and cyclone shelters have greatly reduced the loss of life in recent years.
Floods occur when rivers overflow their banks due to heavy rainfall, snowmelt or cyclonic storms. In India, floods are most common in the Ganga-Brahmaputra basin, particularly in Assam, Bihar, Uttar Pradesh and West Bengal. The Brahmaputra river floods almost every year. Floods cause loss of life, destruction of crops and property, and water-borne diseases. Flood control measures include embankments, dams, afforestation and flood forecasting.
A drought is a prolonged period of deficient rainfall causing water shortage. Droughts occur when the monsoon is weak or fails. Drought-prone areas of India include Rajasthan, Gujarat, parts of Maharashtra, Andhra Pradesh and Karnataka. Droughts cause crop failure, famine, shortage of drinking water and livestock loss. Drought management involves water conservation, rainwater harvesting, drought-resistant crops and the development of irrigation.
Landslides are the rapid downslope movement of rock, soil and debris under the influence of gravity. They occur in the Himalayan region, the Western Ghats and the north-eastern states, especially during heavy rainfall. Landslides are caused by heavy rain, earthquakes, steep slopes, deforestation and construction activity. They destroy roads, settlements and farmland. The National Landslide Risk Management Programme addresses this hazard, with mitigation measures including afforestation, terracing and slope stabilisation.
Disaster management involves preparedness, mitigation, response and recovery. The key framework in India includes: - Disaster Management Act, 2005: Established the National Disaster Management Authority (NDMA) and state and district level authorities. - National Disaster Response Force (NDRF): Specialised force for disaster response. - Early warning systems: For cyclones, tsunamis and floods (e.g., INCOIS for tsunamis, IMD for cyclones). - Community awareness and preparedness: Training, mock drills and the involvement of local communities.
The approach has shifted from a relief-oriented approach to a holistic, preparedness-and-mitigation approach. This has significantly reduced the loss of life in recent disasters.
| Hazard | Affected Regions | Main Cause |
|---|---|---|
| Earthquakes | Himalayan belt, NE India, Bhuj | Plate movement along faults |
| Tsunamis | Coastal areas of Tamil Nadu, Andaman | Submarine earthquakes |
| Cyclones | East coast (Odisha, AP, TN, WB) | Warm ocean temperatures |
| Floods | Ganga-Brahmaputra basin | Heavy rainfall, river overflow |
| Droughts | Rajasthan, Gujarat, Maharashtra | Deficient monsoon |
| Landslides | Himalayas, Western Ghats | Heavy rain, steep slopes |
| Component | Agency / Action |
|---|---|
| Legal framework | Disaster Management Act, 2005 |
| Policy body | National Disaster Management Authority (NDMA) |
| Response force | National Disaster Response Force (NDRF) |
| Early warning | IMD (cyclones), INCOIS (tsunamis) |
India is one of the most disaster-prone countries of the world because of its location on active plate boundaries, its monsoon-dominated climate and its varied physiography. Earthquakes threaten the Himalayan region, tsunamis and cyclones strike the coasts, floods devastate the river plains, droughts parch the western and peninsular interiors, and landslides occur on steep mountain slopes. These hazards become disasters when they strike vulnerable populations, causing enormous loss of life and property. India has responded by establishing a comprehensive disaster management framework, including the Disaster Management Act of 2005, the NDMA, the NDRF and modern early warning systems. By shifting from a relief-based approach to one of preparedness, mitigation and community participation, India has significantly reduced the impact of disasters and continues to build resilience against the natural hazards that shape its physical environment.
Keywords: Hazard, disaster, earthquake, focus, epicentre, tsunami, cyclone, flood, drought, landslide, NDMA, NDRF, storm surge.