THE RESTLESS EARTH

THE RESTLESS EARTH

1. STRUCTURE OF THE EARTH

   • crust-25 miles deep oceanic crust is 3-6 miles deep. Mantle-largest 1/2 of the planets mass, dense rocks that move 1600f - 1000f causing tectonic shift Outercore- 100 miles below the earths surface, 4-9,000f liquid metal causing magnetism. Inner Core- 4,000miles below earth crust, metallic, iron 9,000f

2. plates

   • CONVECTION CURRENTS- The core heats the mantle as it is 9,000f. The dense rock of the mantle rises as its heated, As it rises and moves away from its heat source it cools and sinks back down this causes the plates to move.
   • oceanic crust- Can be renewed and destroyed, newer- most less than 2,000 years old, less denser and can sink
   • continental crust- cannot be renewed and destroyed, older- most over 1500 millions years old, denser and cannot sink
   • constructive plat boundary- convection currents are....
     • there is a fissure in the earths crust, magma rises and fills the gap, solidifying and forming new crust
       • e.g is the Eurasion and North american plate. The gaps widening by up to 5cm per year
   • Conservative plate boundary- convection currents are...
     • As the plates slide past each other it is not smooth, this causes a build up of pressure and the release of pressure is an earthquake
       • E.G- The north american and parcific plate, the pacific is sliding past the North american plate at the rate of 10m per year
   • destructive plate boundary-convection currents are...
     • Two plates collide as the oceanic crust is denser it is sub ducts beneath the lighter continental crust. As they life past each other this movement is not smooth this released pressure is an earthquake. the build up of pressure also causes magma to extrude throughout the curst as an explosion volcano. the valley between the two plates u known as an ocean trench each plat is one of the walls of the valleys.
       • E.G- the pacific plate and the eurasion plate amongst others, they create the marinas trench which is the deepest ocean trench and home to the deepst of the ocean, 6.85 miles

3. FOLD MOUNTAINS

   • Fold mountains are located along the side of the west coast of north and south america north east asia including Japan. Found near oceans, small in southern and eastern europe and new zealand. anomlalieis is that the southern asian mountains are not neat the ocean
   • Humans use of fold mountains- 1. farming in urubamba river valley 2.mining in yanacocha 3. tourism 4. hydroelectric power
   • disadvantages- difficult to build roads railways and houses. Few industries or other types of jobs. Risk of avalanches and Earthquakes

4. OCEAN TENCHES

   • 1. occur at destructive plate boundaries, deep typically 5,000-10,000m 2. it is sub-duction which is the trench 3. one wall is formed by the sub-ducted oceanic plate 4. other wall is formed by the overriding continental plate

5. VOLCANOES

   • SHEILD VOLCANO
     • it is made from solidified lave, has gentle sloping sides and the base is very wide, the type of eruption is regular and gentle e.g mauna loa, hawaii. it forms at the constructive plat boundary- convection current heats surrounding rocks within the mantle. as the rock is less dense it rises and moves away from the heat source, becomes less dense and sinks oceanic plates move apart, Magma rises to fill the gap, alva then flows solidify and form the sides.
   • COMPOSITE CONE
     • it is made from alternate layers of ash and lave, has steep sloping side and a narrow bee, the eruption is less frequent but explosive eruptions. E.G mt pinatubo philippines. It is formed on the destructive plat boundary- convection currents heats the surrounding rocks within the mantle, as rock is less dense it rises and moves away from heat source, becomes dense and sinks. oceanic plate is denser so is sub ducted fand destroyed in the mantle, pressure builds up and magma extrudes throughout the crust forming an explosive volcano
   • volcanoes are monitored by seismometer which indicates crustal movement. also thermal imaging techniques which indicates movement of magma due to increased heat detected. also gas samples mat be taken and chemical sensor used to measure sulphur levels which indicates movement of magma due to release of sulphur

6. SUPER VOLCANOES

   • are mega colossi volcano that erupt 1000km3 of material
     • no volcano cone, calderas in crust, occur at hotstops
       • 1. rising magma cannot escape and a large bulge appears on the surface 2. cracks appear in the surface and gas and ask erupt from the magma chamber 3. the magma chamber collapses forming a depression called caldera
         • yellowstone- west coast of north america, caldera is 55 km by 72 km. magma chamber is 80 km long, 40km wide and 8 km deep
           • immediate effects on area- 1. 87,000 deaths (Predicted) 2. large as clouds 40-50km into atmosphere 3. destruction of 1,000km of land 4. ash 15cm thick covering building 1,00km
             • world wide effects- 1. sulphur gas goes into the upper atmosphere, climate cooling, then 5 days after the eruption the uk would see an ash fall, temperatures would fall between 12oc and 15oc, parts of europe america and asia would see constant snow cover for 3 years, crops would fail
   • advantages of living in areas of volcanic activity- minerals in chilee e.g sulphur which is sold for $800 per tonne, farming employment is high in plain campania, soil is 8x more fertile, tourism is goos pompeii gets 2.5 million tourists, geo-thermal energy is very cheap, iceland gets 85% of energy
     • disadvantages are poverty since tied to their income. risk of death and serious injury

Images and files in the map