GEOGRAPHY NATURAL HAZARDS TERM 2 – Flashcards

the movements of tetonic plates.

Plates are the segments into which the crust of the earth is divided

they are pushed together-an edge is created-convergent plate boundary plates pull apart-divergent plate boundary plates slide past each other-transform plate boundary

convergent and divergent

ash fall lava flows

a risk of a threatening situation that occurs in the environment

is a hazard brought about due to man's actions or neglect examples: leakage of radioactive emissions,oil spills

an unpredictable threat that occurs in a climatic,physical,biotic environment

the realization of a threat where harm and damage is done to humans,animals and their property

a hazard that originates in the atmosphere

climatic geophysical biotic

hurricanes,drought,flood,snowstorms

earthquake,volcanic eruptions,tsunami,floods,landslides

one that originates due to occurrences on and below the land

hazards that are brought about by plants and/or animals or that affects plants and/or animals

epidemics,forest fires,plant diseases,pests

pyroclastic flow-large masses of gas,ash and lava fragments which rush down the sides of the volcano mudflows or lahars volcanic bombs

cannot be prevented monitoring-active volcanoes and dormant ones can be monitored at scientific centres-signs that can be monitored are small earthquakes,bulges at the sides of the volcano and increase in sulphurous gases that are emitted land use planning-before volcanic activity occurs,a parameter around the volcano can be designated as unsafe and either used for only certain activities or not used at all. In the event of a volcanic eruption,this area can be increased to create an exclusion zone re-construction-after volcanic activity,the government can put things in place to allow the country to resume normal activity for example funds set up for natural disasters or aid given by other countries education-through the use of media and educational institutions citizens can learn the proper behaviours before,during and after an eruption

ground shaking and displacement-as the waves of the earthquake arrive at the surface of the earth,the ground moves. collapse of buildings and infrastructure-ground shaking causes buildings to sway,move back or forth and lurch up and down. the movement also shatters windows and roofs collapse. death and injuries-people are hit by flying or collapsing debris shaking can cause the ground on steep slopes or the ground that has weak rock below it to slip away. landslides can destroy everything fires-ground shaking can cause lamps stoves and candles to topple over floods-bursting of dams tsunamis

planning-land use planning can encourage persons to build in safe areas building design-use steel beams in contruction,attach buildings to their foundations with anchor bolts,strap large items to the wall follow given building codes education and preparation-have evacuation drills

movements at plate boundaries cause faults to develop and faulting to occur. Due to faulting,movement begins but each fault block is held in place by friction. This causes pressure to build. Eventually,the faulting overcomes the friction and the pressure is released as energy which we feel as an earthquake.

the point below the earth's surface where the most movement takes place and the most energy is released

the point on the surface of the earth which lies directly above the focus

small earthquakes felt before the major earthquake

smaller earthquakes felt after the major earthquake

richter scale mercalli scale

a condition whereby an area has less precipitation than normal over a few months or even years

climate change/global warming-increase in temperature causes a number of reactions among which are droughts changes in the local landscape due to human activities (deforestation for example)-deforestation reduces the soil's ability to transmit water to deeper levels of the ground and reduces evapotranspiration that could lead to local rainfall. changes in the ocean temperatures brought on by El Nino which is an atmospheric phenomenon that causes the exchange of moisture between places west of the pacific and east of the pacific

crops fail because of no water for irrigation famine malnutrition death livestock perish creation of refugees/migrants reduction of wildlife which affects biodiversitiy increased soil erosion

monitor water reserves and rainfall activity reduce water loss-repair seepages and leaks in aged pipes and regulate water use and water meters create water reserves protect catchment areas

A flood is a body of water that temporarily covers land that is usually dry and considered useful to man when dry.

1)Heavy or prolonged rainfall-intense rainfall,that is, a large volume of rain falls in a short space of time or rain falls continuously over several hours or even days,rainwater will not be able to penetrate into the soil either because the drops are too large or the soil is saturated with water. 2)Deforestation-trees break the large drops of intense rainfall into smaller drops which can penetrate into the soil(interception.) So if no trees are there,the water will simply flow over the surface. 3)Solid waste in waterways-litter of various types clog waterways and cause the water level in rivers etc. to rise quickly whenever rain falls. 4)Impermeable surfaces/hard surfaces-some soils do not allow water to pass through so after heavy rainfall,flooding will result.Also man-made impermeable surfaces such as paved roads and concrete yards also prevent water from penetrating into the soil. 5)Coastal flooding-the movement of waves beyond the high tide level.It happens because of a tsunami or a storm surge caused by hurricanes.

Because of the man made impermeable surfaces such as concrete yards and paved roads which prevent water from penetrating into the soil.

loss of crops-prices of food crops will rise roads are blocked spread of diseases-cholera,malaria,dengue,leptospirosis loss of life loss of property homes are flooded landslides polluted portable water

build a dam dredge the river(widen and deepen the river) raise height of river bank remove/stop solid waste landzoning-avoid building near rivers and coastlines reforestation

A series of long,high sea waves brought about by earthquakes,volcanic activity that occurs underwater or landslides

underwater volcanoes,earthquakes or landslides. all tsunamis are caused because of a bulge caused by: the power of the volcanic eruption the displacement of water in a landslide underwater plate movement all these movements trigger giant waves and these waves travel at speeds up to 500 km/hr.They travel in a circular motion,outwards in all directions from where they originate.

death-deadly currents sweep people away,causing them to drown trees are uprooted and animals drown buildings,infrastructure and personal property are destroyed destruction of homes,buildings and infrastructure near the coast risk of disease created by stagnant and contaminated water

countries within and surrounding major oceans can network together to create Tsunami Warning Systems e.g. Pacific Tsunami Warning System create alarm systems to warn persons who are near the coast,to head for higher ground. encourage development away from coast,in areas prone to tsunamis. countries can educate their population about measures to take when a tsunami is approaching-if the sea suddenly recedes,run for higher ground etc.

A tornado is a rapidly rotating column of air that forms under a thundercloud.It is sometimes called a twister. Tornado winds exceed 480 km/h

Thunderstorms that lead to tornadoes form when warm moist air and a cold front meets:before the thunderstorm,a horizontal rotating column of air forms.The rising air that helps to form the thunderstorm changes the rotating column from horizontal to vertical.Eventually,the entire thundercloud gets caught up in this rotating column.The lower base if the cloud eventually touches the ground and a tornado is formed.

destruction of homes and property entire fields of crops can be lost animals are killed people are killed and/or injured

things can be done to prevent damage/minimise damage: build bunkers or basements in your home ensure that people/objects are tied down severely insure(insurance)property/properties against disasters families can create emergency plans

an intense low pressure weather system(500-1500 km wide) with bands of strong winds (over 119 km/h)that spiral around a central area called the eye

A hurricane is given for these systems that originate in the Atlantic Ocean. A typhoon originates in the Indian Ocean A cyclone originates in the Pacific Ocean

warm temperatures of at least 26 degrees Celcius a large source of moisture such as the ocean spiraling winds which usually occur more than 10 degrees North and South latitude-this is because spiraling winds are a result of the Coriolis force which is formed when the earth spins on its axis divergent outflow in the upper atmosphere(10 km above)

1)tropical disturbance-an area with heavy and sustained thunderstorm activity-can be caused by the Inter tropical convergence zone or a tropical wave-begins off the coast 2)Tropical depression-weather disturbance intensifies,inflow of warm air from ocean surface,weak spiralling pattern develops, pressure drops, wind speeds 62 km/h 3) tropical storm-winds become organized, strong circular movement gives rise to an eye, lower pressure, wind speeds increase 63-118 km/h, the system gets a name 4) hurricane-eye of hurricane is visible in satellite imagery, low pressure, wind speeds greater than 119 km/hr, growth and intensification is measured using a saffir 5) death-lose power as they approach higher latitudes because the temperature is lower, lose power as they move over large continents because it needs moisture,

Trees are blown over Flooding caused by heavy rainfall destroy crops Flooding Also leaves large scale soil erosion Houses are damaged or destroyed Power lines are brought down Roads are blocked People are killed the economy suffers as sources of income such as agriculture and tourism are affected tourism is challenged because of the damage to hotels

individuals should know what to do before,during and after a hurricane government responses-meteorological offices can track hurricanes so that they can provide better information to the public educate pupils in school and adults via the media about the dangers of hurricanes and ways to reduce damage ODPM-national agencies can collaberate with other agencies to coordinate disaster response activities

A down slope movement of a large mass of soil and rocks under the influence of gravity

Natural: torrential rainfall-when a large amount of water finds its way into the sil and the rocks on the slope,it gets in between the soil particles and rock spaces,loosening the bonds that hold them together and cause them to be more easily moved by gravity slopes that have permeable rocks resting on impermeable rock-permeable rock allows water to pass through it,impermeable rock does not allow water to pass through it. When rain falls,the water sinks through the permeable rock but remains as a layer above the impermeable rocks. The makes the top of the rock slippery and the soil slides down the slope. seismic activity-the shaking that results from earthquakes helps to loosen the bonds between soil and rock particles,allowing them to be pulled down by gravity.

cutting a road into hillsides-this increases the slope angle and leaves part of the slope unsupported so it is easily brought down by earthquakes and rainfall constructing buildings and infrastructure on slopes-this places an additional weight on the slope making it vulnerable to natural triggers of landslides leaking pipes and sewers-this can cause the soil to become heavier(water gives additional weight) and gravity overcomes the forces holding the soil/rock together quarrying-loosens rocks and soil particles making them vulnerable to the force of gravity. the removal of vegetation can also increase the likelihood of landslides.

people die as stones and soil cover them damage to homes and property as the land beneath a house gives away,it collapses and is destroyed. debris can also destroy it roads are blocked cutting communities off one another rivers are dammed and it can eventually lead to flooding valuable top soil is lost,hindering agricultural activity removal of vegetation/forest cover

landslide hazard mapping-areas should be tested for landslide vulnerability and major developments should be prohibited in areas that are high risk landslide zones build restraining structures such as retaining walls steep slopes can be graded into gentler ones repair any leaking pipes and sewage mains