A natural disaster is a natural event, such as an earthquake, flood, or hurricane, which negatively affects society, either through damage to property or through loss of life. A natural hazard is a disaster that has not yet occurred. Natural events are often referred to as natural hazards when referring to the general phenomenon, but they are called natural disasters when referring to a specific event, such as the 2004 Indian Ocean earthquake and tsunami or Hurricane Katrina. If a natural event does not pose any risk to human property or lives, it is simply a natural event; hazards and disasters only occur in conjunction with human society.
According to UNISDR (2009)
A dangerous phenomenon, substance, human activity or condition that may cause loss of life, injury or other health impacts, property damage, loss of livelihoods and services, social and economic disruption, or environmental damage.
Some examples of hazards include:
i. Absence/abundance of rain
Both absence and abundance of rain can cause hazards of unpredictable dimensions. Absence of rain can cause drought conditions. Recurring droughts could have cascading effects leading to crop failures and the resultant.
conflicts, famines and mass migration. Abundance of rain could result in floods that can cause large scale devastation to properly and human life.
ii. Incorrect agricultural practices and methods
A number of incorrect agricultural practices could lead to hazards that can cause untold miseries to generations. An example is the indiscriminate aerial spraying of the dreaded pesticide Endosulfan by the stale run Plantation Corporation of Kerala on its cashew plantations, in the northern part of Kerala. This resulted in a number of death, and diseases to the local population. The water bodies in the locality also got severely contaminated. The situation is so grave that ladies in the area are afraid of conceiving, due to the high level of malformed fetus.
iii. Factories involved in hazardous operation near settlements
Those chemical plants involved in hazardous operations that are situated near settlements can lead to hazards of untold proportions. The accident that occurred in the Union Carbide factory in Bhopal is a classical example of such a hazard. The memory of Bhopal gas tragedy is still ripe in everyone’s memory, though it occurred over quarter of a century back.
Types of natural hazards
Natural hazards fall into four main categories depending upon the driving forces of the event: geological hazards, atmospheric hazards, hydrological hazards, and biological hazards.
• Geological hazards occur because of geological processes such as movement in the tectonic plates and volcanic activity. These events include earthquakes, volcanic eruptions, and landslides.
• Meteorological hazards occur as a result of processes in the atmosphere. Meteorological hazards include extreme temperatures, hurricanes, tornadoes, droughts, and severe storms.
• Hydrological hazards are hazards involving water processes. Examples include floods, droughts, and tsunamis.
• Biological hazards occur due to the biological processes of the earth and primarily involve the spread of diseases and pests. Epidemics, pandemics, and insect swarms all fall into the biological hazards category.
Natural hazards also fit into three categories that describe the speed and extent of a hazard: catastrophic hazards, rapid onset hazards, and slow onset hazards.
• Catastrophic hazards are large-scale that effect large numbers of people or have worldwide effects. Pandemics, large volcanic eruptions, and worldwide droughts are all examples of catastrophic natural hazards.
• Rapid onset hazards occur quickly and with little warning. Volcanic eruptions, earthquakes, flash floods, and landslides are examples of rapid onset hazards.
• Slow onset hazards occur slowly and may take years to develop. Epidemics, insect infestations, and droughts are all slow onset hazards.