Transcript Disasters
Disasters Prepared by: Arthur Puzinas Disasters (disambiguation) A disaster (from Middle French désastre, from Old Italian disastro, from Latin pejorative prefix dis- bad + astrum star) is the impact of a natural or man-made hazard that negatively affects society or environment. Disasters occur when hazards strike in vulnerable areas. Disasters are generally more limited in scale than doomsday events, the global impact of which would threaten a large proportion of life on earth. The word disaster's root is from astrology: this implies that when the stars are in a bad position a bad event will happen. Sorts of natural disasters They are: avalanche, cold, drought, earthquake, epidemics, fire, famine, flood, hail, heat, landslide, limnic eruption, sinkhole, solar flare, storm surge, thunderstorm, tornado, tropical cyclones, tsunami, volcanic eruption, waterspout and winter storm. The Avalanche An avalanche is a very large slide of snow (or rock) down a mountainside, caused when a buildup of snow is released down a slope, and is one of the major dangers faced in the mountains. An avalanche consists of rapidly moving granular material that has exceeded the critical static friction threshold and thereby causes additional material to exceed it's threshold as well, in a cascading effect. In an avalanche, lots of material or mixtures of different types of material fall or slide rapidly under the force of gravity. Avalanches are often classified by what they are made of, for example snow, ice, rock or soil avalanches. A mixture of these would be called a debris avalanche. A large avalanche can run for many miles, and can create massive destruction of the lower forest and anything else in its path. For example, in Montroc, France, in 1999 300,000 cubic metres of snow slid on a 30 degree slope, achieving a speed of 100 km/h (60 mph). It killed 12 people in their chalets under 100,000 tons of snow, 5 meters (15 feet) deep. The Mayor of Chamonix was convicted of second-degree murder for not evacuating the area, but received a suspended sentence[1]. The Drought A drought is a period of time when there is not enough water to support agricultural, urban or environmental water needs. A drought usually refers to an extended period of below-normal rainfall, but can also be caused by drying bores or lakes, or anything that reduces the amount of liquid water available. Although what is considered "normal" varies from one region to another, drought is a recurring feature of nearly all the world's climatic regions. The effects of drought vary greatly, depending on agricultural, urban and environmental water needs. And in Which water companies,and farmers suffer. The Flood A flood (in Old English flod, a word common to Teutonic languages; compare German Flut, Dutch vloed from the same root as is seen in flow, float) is an overflow of water, an expanse of water submerging land, a deluge.[1] In the sense of "flowing water", the word is applied to the inflow of the tide, as opposed to the outflow or "ebb". The Flood, the great Universal Deluge of myth and perhaps of history is treated at Deluge in mythology. Floods from the sea can cause overflow or overtopping of flood-defenses like dikes as well as flattening of dunes or bluffs. Land behind the coastal defence may be inundated or experience damage. A flood from sea may be caused by a heavy storm (storm surge), a high tide, a tsunami, or a combination thereof. As many urban communities are located near the coast this is a major threat around the world. Many rivers flow over relatively flat land border on broad flood plains. When heavy the deposition of silt on the rich farmlands and can result in their eventual depletion. The annual cycle of flood and farming was of great significance to many early farming cultures, most famously to the ancient Egyptians of the Nile river and to the Mesopotamians of the Tigris and Euphrates rivers. A flood happens when an area of land, usually low-lying, is covered with water. The worst floods usually occur when a river overflows its banks. An example of this is the January 1999 Queensland floods, which swamped south-eastern Queensland. Floods happen when soil and vegetation cannot absorb all the water. The water then runs off the land in quantities that cannot be carried in stream channels or kept in natural ponds or man-made reservoirs. Limnic Eruption A limnic eruption, also referred to as a lake overturn or exploding lake, is a rare type of natural disaster in which CO2 suddenly erupts from deep lake water, posing the threat of suffocating wildlife, livestock and humans. Such an eruption may also cause tsunamis in the lake as the rising CO2 displaces water. Scientists believe landslides, volcanic activity, or explosions can trigger such an eruption. Some features of limnically active lakes include: CO2-saturated incoming water A cool lake bottom indicating an absence of direct volcanic interaction with lake waters An upper and lower thermal layer with differing CO2 saturations Close proximity to areas with volcanic activity Scientists have recently determined, from investigations into the mass casualties in the 1980s at Lake Monoun and Lake Nyos, that limnic eruptions and volcanic eruptions, although indirectly related, are actually separate types of disaster events. Tropical Cyclones A tropical cyclone is a warm storm system fueled by thunderstorms near its center. It feeds on the heat released when moist air rises and the water vapor in it condenses. The term describes the storm's origin in the tropics and its cyclonic nature, which means that its circulation is counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. Tropical cyclones are distinguished from other cyclonic windstorms such as nor'easters, European windstorms, and polar lows by the heat mechanism that fuels them, which makes them "warm core" storm systems. Depending on their location and strength, there are various terms by which tropical cyclones are known, such as hurricane, typhoon, tropical storm, cyclonic storm, and tropical depression. Tropical cyclones can produce extremely strong winds, tornadoes, torrential rain, high waves, and storm surge. They are born and sustained over large bodies of warm water, and lose their strength over land. This is the reason coastal regions can receive significant damage from a tropical cyclone, while inland regions are relatively safe from receiving strong winds. Heavy rains, however, can produce significant flooding inland, and storm surges can produce extensive coastal flooding up to 25 miles/40 km inland. Although their effects on human populations can be devastating, tropical cyclones can also relieve drought conditions. They carry heat away from the tropics, an important mechanism of the global atmospheric circulation that helps maintain equilibrium in the Earth's troposphere.