DisastersDisasters

Prepared by: Arthur PuzinasPrepared by: Arthur Puzinas

Disasters (disambiguation)Disasters (disambiguation) A A disasterdisaster (from Middle French désastre, from (from Middle French désastre, from

Old Italian disastro, from Latin pejorative prefix Old Italian disastro, from Latin pejorative prefix dis- bad + astrum star) is the impact of a dis- bad + astrum star) is the impact of a naturalnatural or man-made hazard that negatively affects or man-made hazard that negatively affects society or society or environmentenvironment. Disasters occur when . Disasters occur when hazards strike in vulnerable areas. Disasters are hazards strike in vulnerable areas. Disasters are generally more limited in scale than doomsday generally more limited in scale than doomsday events, the global impact of which would events, the global impact of which would threaten a large proportion of life on earth. The threaten a large proportion of life on earth. The word disaster's root is from astrology: this word disaster's root is from astrology: this implies that when the stars are in a bad position implies that when the stars are in a bad position a bad event will happen.a bad event will happen.

Sorts of natural disastersSorts 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 AvalancheThe Avalanche An An avalancheavalanche is a very large slide of snow (or rock) down a is a very large slide of snow (or rock) down a

mountainside, caused when a buildup of mountainside, caused when a buildup of snowsnow is released down a is released down a slope, and is one of the major dangers faced in the slope, and is one of the major dangers faced in the mountainsmountains. An . An avalanche consists of rapidly moving avalanche consists of rapidly moving granulargranular materialmaterial that has that has exceeded the critical exceeded the critical staticstatic frictionfriction threshold and thereby causes threshold and thereby causes additional material to exceed it's threshold as well, in a cascading additional material to exceed it's threshold as well, in a cascading effect.effect.

In an avalanche, lots of material or mixtures of different types of In an avalanche, lots of material or mixtures of different types of material fall or slide rapidly under the force of material fall or slide rapidly under the force of gravitygravity. Avalanches are . Avalanches are often classified by what they are made of, for example snow, ice, often classified by what they are made of, for example snow, ice, rockrock or or soilsoil avalanchesavalanches. A mixture of these would be called a debris . A mixture of these would be called a debris avalanche.avalanche.

A large avalanche can run for many miles, and can create massive A large avalanche can run for many miles, and can create massive destruction of the lower forest and anything else in its path. For destruction of the lower forest and anything else in its path. For example, in example, in MontrocMontroc, , FranceFrance, in 1999 300,000 cubic metres of snow , in 1999 300,000 cubic metres of snow slid on a 30 degree slope, achieving a speed of 100 km/h (60 mph). It 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 killed 12 people in their chalets under 100,000 tons of snow, 5 meters (15 feet) deep. The Mayor of (15 feet) deep. The Mayor of ChamonixChamonix was convicted of second- was convicted of second-degree murder for not evacuating the area, but received a suspended degree murder for not evacuating the area, but received a suspended sentencesentence[1][1]..

The DroughtThe Drought

A A droughtdrought is a period of time when there is not enough is a period of time when there is not enough waterwater to to support agricultural, urban or environmental water needs. A support agricultural, urban or environmental water needs. A drought usually refers to an extended period of below-normal drought usually refers to an extended period of below-normal rainfallrainfall, but can also be caused by drying , but can also be caused by drying boresbores or or lakeslakes, or , or anything that reduces the amount of liquid water available. anything that reduces the amount of liquid water available. Although what is considered "normal" varies from one region to Although what is considered "normal" varies from one region to another, drought is a recurring feature of nearly all the world's another, drought is a recurring feature of nearly all the world's climatic regions. The effects of drought vary greatly, depending climatic regions. The effects of drought vary greatly, depending on agricultural, urban and environmental water needs. And in on agricultural, urban and environmental water needs. And in Which water companies,and farmers suffer.Which water companies,and farmers suffer.

The FloodThe Flood A A floodflood (in (in Old Old EnglishEnglish flod, a word common to Teutonic languages; compare flod, a word common to Teutonic languages; compare

German Flut, Dutch vloed from the same root as is seen in flow, float) is an 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.overflow of water, an expanse of water submerging land, a deluge.[1][1] In the In the sense of "flowing water", the word is applied to the inflow of the sense of "flowing water", the word is applied to the inflow of the tidetide, as opposed , as opposed to the outflow or "ebb". The Flood, the great Universal Deluge of myth and to the outflow or "ebb". The Flood, the great Universal Deluge of myth and perhaps of history is treated at perhaps of history is treated at DelugeDeluge in in mythologymythology.. Floods from the sea can Floods from the sea can cause overflow or overtopping of flood-defenses like cause overflow or overtopping of flood-defenses like dikesdikes as well as flattening of as well as flattening of dunesdunes or bluffs. Land behind the coastal defence may be inundated or experience or bluffs. Land behind the coastal defence may be inundated or experience damage. A flood from sea may be caused by a heavy storm (damage. A flood from sea may be caused by a heavy storm (stormstorm surgesurge), a high ), a high tide, a tide, a tsunamitsunami, or a combination thereof. As many urban communities are , or a combination thereof. As many urban communities are located near the coast this is a major threat around the world. Many rivers flow located near the coast this is a major threat around the world. Many rivers flow over relatively flat land border on broad over relatively flat land border on broad floodflood plainsplains. When heavy the deposition . When heavy the deposition of silt on the rich farmlands and can result in their eventual depletion. The annual 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 cycle of flood and farming was of great significance to many early farming cultures, most famously to the ancient cultures, most famously to the ancient EgyptiansEgyptians of the of the NileNile river and to the river and to the MesopotamiansMesopotamians of the of the TigrisTigris and and EuphratesEuphrates rivers. rivers.

A flood happens when an area of land, usually low-lying, is covered with water. 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 The worst floods usually occur when a river overflows its banks. An example of this is the January 1999 this is the January 1999 QueenslandQueensland floods, which swamped south-eastern floods, which swamped south-eastern Queensland. Floods happen when soil and vegetation cannot absorb all the 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 water. The water then runs off the land in quantities that cannot be carried in stream channels or kept in natural ponds or man-madestream channels or kept in natural ponds or man-made reservoirs.reservoirs.

Limnic EruptionLimnic Eruption A A limnic eruptionlimnic eruption, also referred to as a , also referred to as a lake overturnlake overturn or or exploding exploding

lakelake, is a rare type of , is a rare type of natural disasternatural disaster in which in which CO2CO2 suddenly erupts suddenly erupts from deep lake water, posing the threat of suffocating wildlife, from deep lake water, posing the threat of suffocating wildlife, livestock and humans. Such an eruption may also cause livestock and humans. Such an eruption may also cause tsunamistsunamis in in the lake as the rising CO2 displaces water. Scientists believe the lake as the rising CO2 displaces water. Scientists believe landslideslandslides, , volcanicvolcanic activity, or explosions can trigger such an activity, or explosions can trigger such an eruption. Some features of limnically active lakes include:eruption. Some features of limnically active lakes include:

CO2-saturated incoming water CO2-saturated incoming water A cool lake bottom indicating an absence of direct volcanic interaction A cool lake bottom indicating an absence of direct volcanic interaction

with lake waters with lake waters An upper and lower thermal layer with differing CO2 saturations An upper and lower thermal layer with differing CO2 saturations Close proximity to areas with volcanic activity Close proximity to areas with volcanic activity Scientists have recently determined, from investigations into the Scientists have recently determined, from investigations into the

mass casualties in the mass casualties in the 1980s1980s at at LakeLake MonounMonoun and and LakeLake NyosNyos, that , that limnic eruptions and volcanic eruptions, although indirectly related, limnic eruptions and volcanic eruptions, although indirectly related, are actually separate types of disaster events.are actually separate types of disaster events.

Tropical CyclonesTropical Cyclones A A tropical cyclonetropical cyclone is a warm storm system fueled by thunderstorms near its 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 center. It feeds on the heat released when moist air rises and the water vapor in it in it condensescondenses. The term describes the storm's origin in the . The term describes the storm's origin in the tropicstropics and its and its cycloniccyclonic nature, which means that its circulation is nature, which means that its circulation is counterclockwisecounterclockwise in the in the NorthernNorthern HemisphereHemisphere and clockwise in the and clockwise in the SouthernSouthern HemisphereHemisphere . Tropical . Tropical cyclones are distinguished from other cyclonic windstorms such as cyclones are distinguished from other cyclonic windstorms such as nor'eastersnor'easters, , EuropeanEuropean windstormswindstorms, and , and polarpolar lowslows by the heat mechanism that fuels them, by the heat mechanism that fuels them, which makes them "warm core" storm systems. Depending on their location which makes them "warm core" storm systems. Depending on their location and strength, there are various terms by which tropical cyclones are known, and strength, there are various terms by which tropical cyclones are known, such as such as hurricanehurricane, , typhoontyphoon, , tropical stormtropical storm, , cyclonic stormcyclonic storm, and , and tropical tropical depressiondepression..

Tropical cyclones can produce extremely strong winds, Tropical cyclones can produce extremely strong winds, tornadoestornadoes, torrential , torrential rainrain, high waves, and storm surge. They are born and sustained over large , 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 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 coastal regions can receive significant damage from a tropical cyclone, while inland regions are relatively safe from receiving strong winds. Heavy rains, inland regions are relatively safe from receiving strong winds. Heavy rains, however, can produce significant flooding inland, and storm surges can however, can produce significant flooding inland, and storm surges can produce extensive coastal flooding up to 25 miles/40 km inland. Although their produce extensive coastal flooding up to 25 miles/40 km inland. Although their effects on human populations can be devastating, tropical cyclones can also effects on human populations can be devastating, tropical cyclones can also relieve drought conditions. They carry heat away from the tropics, an important relieve drought conditions. They carry heat away from the tropics, an important mechanism of the global atmospheric circulation that helps maintain equilibrium mechanism of the global atmospheric circulation that helps maintain equilibrium in the Earth's troposphere.in the Earth's troposphere.