geography eoy y9

• if two continental plates collide, they are both buoyant and so cannot sink into the mantle. As a result, compression forces the plate to collide and form fold mountains.
• if an oceanic and a continental plate move towards each other, the denser oceanic plate is subjected and sinks under the continental plate and into the earth's mantle, where it is recycled. Earthquakes, fold mountains and volcanoes occur
• a constructive plate margin occurs when platers move apart. volcanoes are formed as magma wells up to fill the gap and eventually a new crust is formed. Earthquakes occur here also
• convection currents: movement within the Earth's mantle caused by the heat of the core
• plate margins: where two or more plates meet
• destructive plate margins occur when tectonic plates move towards each other and collide. this effect this has depends on what kinds of plates are colliding
• a conservative plate margin occurs where plates slide past each other in opposite directions, or in the same direction but at different speeds. Friction is eventually overcome and the plates slip past in sudden movements. the shockwaves created produce an earthquake
• the outer core is 2,000km thick and is a liquid
• the mantle is semi-molten and about 3,000km thick
• the crust is the rocky outer layer; it is thin compared to the other sections, approximately 5 to 70km thivk
• A shield volcano has gently sloping sides and runny lava that covers a wide area
• a composite volcano is steep sided and cone shaped, it is made up of layers of ash and lava. the lava is sticky so it does not flow far
• atmospheric- relating to weather
• geomorphological- related to mass movement/ gravity acting on the land
• tectonic- related to mass movements of the earth's crust
• prediction- using technology to estimate when and where we think an earthquake is going to happen
• protection- putting measures in place to help protect people during an earthquake. the most important and common one is building special buildings that will not collapse
• preparation- this is all about getting ready for when the next one comes. it includes special drills and practices so people know what to do and preparing materials in advance
• superpowers- countries that are very powerful and have a lot of influence over other countries. they may have a strong army, cover a large area or be very rich
• the three gorges dam opened in may 2006 and is the most expensive dam ever constructed. it controls flooding-before the dam in 1954 the Yangtze River flooded, which killed around 30,000 people
• tundra- coldest biome- very little precipitation with freezing temperatures. winters are long and summers are short. part of the soil is frozen all year round, although the top part defrosts in summer and plants such as mosses can grow
• taiga- characterised by coniferous forests consisting mostly of pines, spruces and larches
• steppe- characterised by large areas of flat unforeseen grassland
• temperate forests- characterised by high precipitation and mild climates with deciduous trees, mosses, ferns and lichen
• a biome is a large scale ecosystem with distinctive climatic and vegetation (plant life) characterisitcs
• geology- rock type affects the severity of a hazard. an earthquake in an area of soft rock is larger and lasts longer than one in an area of hard rock. soft rock also makes the risk of liquefaction greater
• factors that influence the level of impact- geology, magnitude, frequency, population density, level of development, management, time, education
• education- teaching the population how to prepare and respond to an earthquake can reduce the hazard risk
• time- time of the day the hazard occurs can affect the level of risk
• management- the amount of preparation a country has in place for natural hazards can help to reduce hazard risk
• level of development- the more developed a population, the more chance there is that they are prepared for a hazard
• population density- the greater the number of people there are in an area, the greater the risk. a hazard wich occurs in a sparsely populated area would have a lower impact
• frequency- this is how often the hazard occurs. larger more devastating earthquakes are rare whereas floods can occur annually. the more often a population is affected a hazard, the more likely they are to adapt their way of life to cope
• intermediate technology- using tools and techniques that are suitable for their country of use eg basic tools in countries where they cannot afford to maintain expensive machinery