The term natural Disaster makes reference to the enormous material losses caused by events or phenomena like earthquakes, floods, slidings of earth, deforestation, environmental contamination and others.
The natural phenomena, like rain, earthquakes, hurricanes or the wind, become disaster when they surpass a normality limit (threshold, in English), measured generallythrough a parameter. This one varies following the type of at the moment Seismic phenomenon Magnitude (Mw) (scale of Richter for seismic movements, Saphir-Simpson scale for hurricanes, etc.).
The disasters are caused by the human activities, that alter the normality of the environment. Some of these we have: the contamination of the environment, the erroneous and irrational operation of the renewableas forests and the ground and nonrenewable natural resources like minerals, the construction of houses and constructions in zones of high risk. The effects of a disaster can be amplified due to a bad planning of the slumses, lacking of plan, safety measures of emergencia and systems of alert brought about by the man a little diffuse becomes.
In order institutional capacity to reduce the collectiverisk to it of disasters, these can trigger other events that will reduce the possibility of surviving this one due to deficiencies in the planning and the safety measures. A classic example is the earthquakes, that collapse buildings and houses, leaving catched to people between the rubbish and breaking gas pipes that can catch fire and burn to the wounded under the ruins. The human activity inareas with high probability of natural disasters is known like high risk. Appropriate zones of high risk without instrumentation nor measured to respond to the natural disaster or to reduce their negative effects are known like zones of high vulnerability.
The main institutes that approach this discipline are the International for Institute Applied Systems Analysis (IIASA) of Austria, theProVention Consortium, the Earth Institute of the University of Columbia, the National Center of Prevention of Desastres (CENAPRED) in Mexico, and the University of Kobe in Japan, as well as the special organisms of the UN like the OCHA (Cooperation for Humanitarian Aid), ISDR (Strategy the International for the Reduction of Disasters), as well as offices in the World Bank, the Cepal and the SEE. Thedisasters are not natural, the phenomena are natural. The disasters always appear by the action of the man in their surroundings. For example: a hurricane in the middle of the ocean is not a disaster, unless it passes a ship that way.
It is a complex event that involves a group of waves of great energy and variable size that they take place when some extraordinary phenomenon vertically movesa great mass of water. This type of waves the superficial waves produced by the wind remove an amount of water far beyond. One calculates that 90% of these phenomena are caused by earthquakes, in which case receive the most correct and precise name of “tectonic tidal waves”. The energy of a tidal wave depends on its height (amplitude of the wave) and on its speed. The unloaded total energy on acoastal zone also will depend on the amount of tips that takes the wave train (in the tidal wave of the 2004 Indian Ocean there were 7 enormous, giant and very wide tips). He is frequent that tsunami that travels great distances, diminishes the height of its waves, but it maintains his speed, being a mass of water of little height that devastates yet to its passage towards the interior.
Itis a shock of the land that takes place due to the shock of the tectonic plates and to the energy liberation during an abrupt reorganization of materials of the terrestrial crust. Most important and frequent they take place when accumulated elastic potential energy in the gradual deformation of contiguous rocks is freed to the plane of an active fault, but also can happen by other causes, for...
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