Natural Disasters

Disaster

Disaster: It is defined as a serios disruption of the functioning of a society involving widespread human, material, economic and environmental losses and impacts which exceeds the ability of the affected community or society to cope using it’s own resources.

Types of Disasters

1. Man-Made Disasters

   1. Nuclear Disasters
   2. Chemical Disasters

2. Natural Disasters: It is a major adverse event resulting from natural processes of the Earth such as

   1. Earthquakes
   2. Floods
   3. Landslide
   4. Hurricane/Cyclone
   5. Drought

Natural Disasters

Earthquake

==It is the result of a sudden release of energy in the Earth’s crust that creates seismic waves==. At the Earth’s surface, earthquakes manifest themselves by shaking and sometimes displacement of the ground.

Seismic Activity: It refers to the frequency, type and size of earthquakes experience over a period of time in a given area and are measured using seismometers.

Earthquakes are measured using observations from seismometer and moment magnitude is expressed in terms of Richer scale.

When the epicenter of a large earthquake is located offshore, the seabed may be displaced sufficiently and cause a tsunami.

Floods

Flood: ==It is an overflow of water that submerges land==. It may occur as an overflow of water from water bodies such as a river or lake in which water overtops resulting in some of that water escaping it’s usual boundaries or it may occur due to an accumulation of rainwater on saturated ground in an areal flood.

Floods often cause damage to livelihood and structures. ==The most common classifications of floods are 10-year flood, 50-year flood and 100-year flood.==

==100-year flood: There is a 1% chance that such a flood could happen in any given year.==

Landslide

Landslide: It is a geological phenomenon that includes a wide range of ground movements such as rock falls, deep failure of slops and shallow debris flows.

Landslides can occur offshore, coastal and onshore environments.

Although the action of gravity is the primary driving force for a landslide to occur, ==a landslide often requires a trigger before being initiated.==

Cyclone

Cyclone: It is an area of closed circular fluid motion rotating in the same direction as the earth.

It is characterized by inward circular winds that rotate anti-clockwise in the northern hemisphere (hurricane) and clockwise in southern hemisphere (cyclone).

Anticyclone: It is the opposite of a cyclone. ==An anticyclone’s winds rotate clockwise in the Northern Hemisphere around a center of high pressure==. Air comes in from above and sinks to the ground. High pressure centers generally have fair weather.

Drought

Drought: It is an extended period when a region receives a deficiency in it’s water supply, weather atmospheric, surface or ground water.

A drought can last for months or years or may be declared after as few as 15 days. ==This occurs when a region receives consistently below average precipitation.==

Man-Made Disasters

Disasters having elements of human intent, negligence, error, failure of human-made systems. Such events result in huge losses of life & property along with damage to people’s mental, physical & social wellbeing. Such man-made disasters are Nuclear disaster, biological / chemical threat, accidental, terrorism, etc. ==The causes of man made disasters are: Ignorance, unawareness, illiteracy, carelessness==. The growth in the application of nuclear science and technology in the fields of power generation, medicine, industry, agriculture, research and defense has led to an increase in the risk of occurrence of Nuclear and Radiological emergencies.

Nuclear and Radiological Emergency/Disaster Scenarios

1. An accident taking place in any nuclear facility of the nuclear fuel cycle including the nuclear reactor, or in a facility using radioactive sources, leading to a large-scale release of radioactivity in the environment.
2. A ‘criticality’ accident in a nuclear fuel cycle facility where an uncontrolled nuclear chain reaction takes place inadvertently leading to bursts of neutrons and gamma radiation (as had happened at Tokaimura, Japan).
3. An accident during the transportation of radioactive material.
4. The malevolent use of radioactive material as Radiological Dispersal Device (RDD) by terrorists for dispersing radioactive material in the environment.
5. A large-scale nuclear disaster resulting from a nuclear weapon attack (as had happened at Hiroshima and Nagasaki in Japan) which would lead to mass casualties and destruction of large areas and properties.

Classification of Biohazards

The US Center for Disease Control classifies biohazards into four biosafety levels as follows:

• BSL-1: Bacteria and Viruses including Bacillus subtilis, some cell cultures, canine hepatitis, and noninfectious bacteria. ==Protection is only facial protection and gloves==
• BSL-2: Bacteria and viruses that cause only mild disease to humans, or are difficult to contract via aerosol in a lab setting such as hepatitis A, B, C, mumps, measles, HIV, etc. ==Protection – use of autoclaves for sterilizing and biological safety cabinets.==
• BSL-3: Bacteria and viruses causing severe to fatal disease in humans. Example: West Nile virus, anthrax, MERS coronavirus. ==Protection – Stringent safety protocols such as the use of respirators to prevent airborne infection.==
• BSL-4: Potentially fatal (to human beings) viruses like Ebola virus, Marburg virus, Lassa fever virus, etc. ==Protection – use of a positive pressure personnel suit, with a segregated air supply==

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