What is a natural disaster?

A natural disaster is the effect of a natural hazard (e.g. flood, tornado, volcano eruption, earthquake, or landslide) that affects the environment, and leads to financial, environmental and/or human losses. The resulting loss depends on the capacity of the population to support or resist the disaster, and their resilience. This understanding is concentrated in the formulation: "disasters occurwhen hazards meet vulnerability." A natural hazard will hence never result in a natural disaster in areas without vulnerability, e.g. strong earthquakes in uninhabited areas. The term natural has consequently been disputed because the events simply are not hazards or disasters without human involvement.
Earthquakes
An Earthquake is a sudden shake of the Earth's crust.The vibrations may vary inmagnitude. The underground point of origin of the earthquake is called the "focus". The point directly above the focus on the surface is called the"epicentre". Earthquakes by themselves rarely kill people or wildlife. It is usually the secondary events that they trigger, such as building collapse, fires, tsunamis (seismic sea waves) and volcanoes, that are actually the human disaster. As many ofthese could be avoided by better construction, safety systems, early warning and evacuation planning, the term unnatural disaster is not unwarranted.
Earthquakes are caused by the discharge of accumulated along geologic faults.
Some of the most significant earthquakes in recent times include:
* The 2004 Indian Ocean earthquake, the second largest earthquake in recorded history, registering amoment magnitude of 9.3. The huge tsunamis triggered by this earthquake cost the lives of at least 229,000 people.
* The 7.6-7.7 2005 Kashmir earthquake, which cost 79,000 lives in Pakistan.
* The 7.7 magnitude July 2006 Java earthquake, which also triggered tsunamis.
* The 7.9 magnitude May 12, 2008 Sichuan earthquake]] in Sichuan Province, China. Death toll at over 61,150 as of May27, 2008.
* The 7.3 magnitude January 12, 2010 Haiti earthquake]].
Lahars
A lahar is a volcanic mudflow or landslide. The 1953 Tangiwai disaster was caused by a lahar, as was the 1985 Armero tragedy in which the town of Armero was buried and an estimated 23,000 people were killed
Volcanic eruptions
* An Eruption may in itself be a disaster due to the explosion of the volcano or thefall of rock but there are several effects that may happen after an eruption that are also hazardous to human life.
* Lava may be produced during the eruption of a volcano a material consisting of superheated rock. There are several different forms which may be either crumbly or gluey. Leaving the volcano this destroys any buildings and plants it encounters.
* Volcanic ash - generallymeaning the cooled ash - may form a cloud, and settle thickly in nearby locations. When mixed with water this forms a concrete like material. In sufficient quantity ash may cause roofs to collapse under its weight but even small quantities will cause ill health if inhaled. Since the ash has the consistency of ground glass it causes abrasion damage to moving parts such as engines.
*Supervolcanoes : According to the Toba catastrophe theory 70 to 75 thousand years ago a super volcanic event at Lake Toba reduced the human population to 10,000 or even 1,000 breeding pairs creating a bottleneck in human evolution. It also killed three quarters of all plant life in the northern hemisphere. The main danger from a supervolcano is the immense cloud of ash which has a disastrous global effect onclimate and temperature for many years.
* Pyroclastic flows consist of a cloud of hot volcanic ash which builds up in the air above under its own weight and streams very rapidly from the mountain burning anything in its path. It is believed that Pompeii was destroyed by a pyroclastic flow.
Water disasters
Floods
Some of the most notable floods include:
* The Huang He (Yellow River) in...