natural hazards

the eath is divided into tectonic plates. there are two types of crust: continental crust which is thin and oceanic crust which is thick. convection currents (mantle) drive the plates to move. The earth is described like a peach, as a peaches skin is very thin like the earths crust, then there is a mantle which is thick like a peach, in the middle there is an outer core (the stone of the peach) and inside that is the inner core.

convergent/destructuve (oceanic and continental)- oceanic plate forced downwards into the mantle forming 'subduction zone'. deep trench is formed and the continental plate forced up into mountin range. oceanic plate melts from the friction and heat from the mantle, magma rises from the continental plate.

convergent/collision (two continental)- two tectonic plates moving apart, each boundary has cracks, its under the water. pressure builds up along the plate boundary until plates jump forward, causing earthquakes.

divergent/constructive- two tectonic plates move apart, each boundary has cracks (faults), it is under the ocean. magma hardens when it reaches the surface which can cause new land, when the plates pull apart it creates small earthquakes.

transform/conservative- they create friction, they can become stuck causing a build up of pressure, finally they snap past each other causing earthquakes.

types of natural hazards- earthquakes, huricane, cyclone, wildfire, snow storm, tornado.

hurricane- the minimum speed is 74mph, for a hurricane to form in the ocean the temperature has to be at least 26.5 degrees to a depth of at least 60m. the main hazards: strongwinds, flooding and storms.

tropical storms- gusts can reach up to 350km/h which could damage loads of houses by ripping off roofs and destroying loads of objects. heavy rainful can cause floods meaning people need to evacuate and creates mudslides, as well as a storm surge which can also cause flooding.

draught- caused by: when there is a long period of high atmospheric pressure. people who suffer: farmers- they need water, lack of crop. goverment- they need to save water. fishamen- lakes and rivers are effected. people who benefit: suncream companys- they will get more money from people buying their product. leisure centres- people go there to cool down. solar panels- they get more energy.

factors affecting the severity of draught- wealth, pollution, rainful, location (are they aware of draught?), weather/climate, demand of water.

LEDCs get affected more; they have lost their homes from hurricanes, so may have to stay behind as they cant afford a new life, however MEDCs can afford to evacuate to live somewhere safe.

prediction- tropical storms can be predicted, it's hard to know exactly where they will hit as they can change direction.

ways to predict- high winds, heavy storms, forecasts, messages, radors images, moniter the area, hurricane centre, satellite imagery, buoys, social media.

how people can be saved from the impacts of tropical storms- evacuate, weather forecast, offer low cost loans, inform about insurence, improve weather stations.

LEDC- educate people so they know what to do when a hurricane approaches, improve land use planning, plant shelter belts of trees along the coast that will shield homes from the effects of the strong winds. MEDC- set up relief camps tp provide food, water and shelter, set up co-operative banks with low interest rates, build embankments or levees around settlements, strengthen houses and roofs.

earthquakes accurately predicted- there is alot of equipment and know where the plates are so they can be predicted but not accurately

preparing- first aid kit, security processions, water for family, emergency plan, be prepared, fire extiguishure, house insurence, foundation bolts, person to contact.

emergency- phone, fire extinguesher, water for 3 days/food, belongings, plans, bucket ext...

prediction methods- patterns in time between previous quakes, animals, fore shocks, ground monitering, satilights in space, hazard maps.

earthquake proof buildings- diagonal steel bars reinforce walls, reinforced concrete walls provide strength and resist rocking from earthquakes, gap between ground and the foundation so shook travels through the base isolators.

hazard spotting in the home- in the atic, nail plywood to the ceiling joints around the chimmney for protection. secure brick chimmneys with light, metal brackets, to prevent bookshelves, cabinets and tall dressers from toppling, fasten them to the wall studs with l shaped brackets. bolt the house to its concrete foundation to prevent it from slipping off, to reduce risk of fiore, strap the water heater to the wall to prevent it from toppling over and breaking a gas line. learn how to shut off the gas, water and electricity.

tectonic hazard preparations and protection

educating the population- drills, schools teach hazards, tourists given info packs, dont store items on shelves, keep away from windows, keep a torch and water supplies, buy a wind-up radio, turn off gas ovens. taking action in a home- under table, first aid kit, remove things from shelves. using new tech- maps, good houses, telling population. new building methods- deep foundations, strong safety. government action- evacuation, making buildings better.

drought- bright lights syndrome: some leave rural areas to go to cities, no money, faith: believes their lives will get better soon, infrastructure: transport links are poor reducing travel actions, tradition: people want to keep their normadic way of life, people are not taught: poor education not taught how to improve their lives and get better jobs else where.

hurricane- over half the population needs to stay with their land to grow their own food, many families have enjoyed living there for generations history, attitude: as years go by people forget the damage caused by hurricanes, poverty, no choice: government allows few people to leave, dependent on jobs: fishing industery, there is tourism, financial crisis, people are taught about tropical storms or how to protect themselves: poor education.

reasons- fertile soils, religion, poverty, income, space, history, cheap energy costs, fishing and mining.

education- schools can teach students about the causes of eruptions, drills can train ordinary people how to evacuate, people can be given advice on what to do if there is an earthquake.

emergency action- danger zones can be sealed off, frequent advice and news updates can be given on radio and tele. loud sirens can be used, ash particles can damage aeroplane engines so flights can be banned.

forward planning- people in danger zones can stock up on things needed in an emergency, concrete shelters can be built, concrete lahar channels can be built to try and divert mudflows, many countries provide clear road signs, people can take out insurence to replace their homes and other possessions.

main methods- GPs- used to measure changes in shape by comparing maps. hydrology- measuring changes in water e.g. the amount of discharge in a river. gas composition- measuring changes in gas (sulpher dioxide) e.g. changes in composition. seismograph- as magma rises through the earth, earthquakes vibrations are detected. ground deformation- volcanoe can bulge as magma rises. thermal imagery- detect changes in temperature of lava.

drought are caused when atmosphere circulation changes, high pressure results, so few clouds form and then less rainfall. high temperatures result in higher evapotranspiration then precipitation so more water is lost in the atmosphere/

effects:

social- food imported and prices rise, tourist industry suffers, water restrictions enforced, suicide rates in farmers increases, drough relief reduces government spending elsewhere, starvation, many families cant afford to send children to school, fights break out, people forced to drink dirty water, charieties send out emergency supplies.

enviromental- water quality declines, algae forms, grazing no longer supports cattle, safari animal species die out, rivers totally dry up, lakes shrink in size.

economic- farmers lose income as crops die, wine industry affected by a drop in grape production, poor harvest increases food prices.

drought has less of an impact in a dry area rather then a densely populated area because there is less need for water.

human activity that makes drought worse- deforestation: means less evaporisation, fewer clouds, less rain and soil erosion. irrigation: for crops means less water for other uses. over grazing: means less grass and more soil erosion.

MEDCs- dams: use to trap water, blocks all the water. deforestation plant: takes salt out of water. drip irrigation: instead of spraying it over the field it goes on only the plant wasting less water.

LEDCs- drought resistant plants: does not use much water. charities: focus on getting clean water, appeal donations. sandform: help prevent water escape.