Man has always been subject to natural disasters over which he has little control. The environmental hazards include volcanic eruptions, earthquakes, landslides, tornadoes, hurricanes and cyclones, storm surges, tsunamis, floods, droughts, blizzards, avalanches, forest-fires, and epidemics. In recently ears, the world has been battered with a series of natural and human induced disasters and has left the world reeling. The disasters have made us painfully aware that although humanity will continue to face disasters, we can act to avoid humanitarian crisis.
A natural disaster has been defined as, ï¿½any aspect of physical environmentï¿½s natural functions that may adversely affect human society to cause social disruption, material damage and/or loss of life, in which case the impact is referred to as a natural disaster or catastrophe.ï¿½ Natural disasters include earthquakes, volcanoes, tsunami, cyclones, floods, droughts, snowstorms, epidemics etc. Some of the hazards like earthquake may cause a tsunami wave at sea, landslides or avalanches on slopes, building damage and fires in urban areas, and flooding due to failure of dams, as well as ground shaking and displacement along faults. Similarly, many natural disasters cause disruption to public hygiene and consequently result in heightened risks to disease transmission.
The natural disasters have been divided into:
(i) rapid-onset, intensive events such as earthquakes and tornadoes, and
(ii) slow onset events which often affect larger areas over longer period of time, such as droughts.
In practice, it is often difficult to distinguish between purely ï¿½naturalï¿½ events and ï¿½human inducedï¿½ events. In one sense, all ï¿½naturalï¿½ disasters can be thought of as human induced since it is the presence of people which denes whether a hazard creates a disaster or not, and many of the natural processes that cause disasters can also be triggered or exacerbated by human action. The composite nature of many disasters also blurs the distinction: the major cause of death due to earthquakes is usually crushing beneath buildings, so is the disaster natural or human induced? Some researchers believe that the difficulty of making this distinction has rendered the division pointless, and prefer to talk of ï¿½environmentalï¿½ hazards which refer to a spectrum with purely natural events at one end and distinctly human induced events at the other (Smith, K. 1966, Environmental Hazards: Assessing Risk and Reducing Disaster, 2nd edition. A brief account of some of the recent disasters are as follows:
Tohoku Earthquake and Fukushima Nuclear Accident On March 11, 2011 an earthquake (Tohoku Earthquake) of magnitude was recorded along the north-eastern coast of Honshu Island of Japan (Fig.6.1). The casualty was about 20,000 killed and over three thousand missing. More than 320,000 people (still March 2012) living in temporary homes. It was Japanï¿½s largest earthquake on record. This was the first time a nuclear emergency had been declared in Japan.
The resultant tsunami from the earthquake completely washed out the city of Sendai and seriously damaged the Fukushima and Daiichi nuclear power plants. Only two of 54 reactors remained in operation. The six meter high tsunami waves entered the nuclear reactors which overheated the reactors. The flooding and earthquake damage hindered the rescue operation. The evidence soon arose of partial meltdown in the reactors, hydrogen explosion destroyed the upper cladding of the reactor building. The Fukushima nuclear accident was a series of ongoing equipment failures. The Nuclear Power Plant meltdown resulted into release of enormous quantity of radioactive material. Fears of radiation leaks led to 1,40,000 residents within a 20 km radius evacuation around the plant while workers suffered radiation exposure and were evacuated at various times. The Fukushima Nuclear Power Plant Disaster is considered to be the largest in Japan and the second largest in the world after the Chernobyl Disaster (April 26, 1986). According to the estimate of Nuclear and Industrial Safety Agency (NISA) the total radiation released into atmosphere was at 770,000 tera becqerels- more than double of its earlier estimate. A study by Weissï¿½ U.N. Committee found exposure to iodine was lower in Fukushima than that at Chernobyl. Still, parents are worried because the Chernobyl cancers did not emerge until a couple of years later.
The Chernobyl Soviet Nuclear Power Plant Explosion the Chernobyl Nuclear Power Plant Explosion took place on 26th April, 1986. This Nuclear Power was located about 13 5 km from the city of Kiev- the capital of Ukraine. Unfortunately, errors in the reactor design and errors in judgment of the personnel of the power plant caused cooling water to start boiling. This caused reactor stress, resulting in energy production increase to ten times the normal level. Temperature reached more than 2000oC, causing fuel rod melting and further cooling water boiling. The extreme pressure in cooling water pipes resulted in cracks, which caused steam escape. At 1.23 A.M. in the night, the escaped steam caused an explosion slamming off the building, starting a major and simultaneously forming an atmospheric cloud containing approximately 185 to 250 million curies of radioactive material. Two days after the explosion, the Swedish National Radio reported that 10,000 times the normal amount of cesium-137 existed in the atmosphere, prompting Moscow to officially respond. The following day over 3,50,000 people were evacuated from within a radius of 30 km of the site of accident. The radioactive cloud was blown north and north-west by wind, causing the first mention of the accident to be after radioactivity measurement in Sweden. The cloud covered a large area in Europe. On May 2, 1986, the cloud even reached the Netherlands, causing fresh fruits and vegetables consumption to be prohibited. After the 1986 Chernobyl accident, more than 6000 thyroid cancers clearly linked to radioactive iodine were found in children and adolescents in the affected region of Chernobyl. Traces of radioactive deposits unique to Cheronobyl were found in nearly every country in the Northern Hemisphere.
Written by princy