Chapter 1 : Restless Earth

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Mind Map on Chapter 1 : Restless Earth, created by laurenclark90 on 04/14/2014.
laurenclark90
Mind Map by laurenclark90, updated more than 1 year ago
laurenclark90
Created by laurenclark90 almost 11 years ago
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Resource summary

Chapter 1 : Restless Earth
  1. Crust - made from thin layers of tectonic plates
    1. Mantle - solid upper part and semi-liquid lower part that can flow
      1. Core - consists of a liquid outer core and solid inner core
      2. Continental crust (30-60km) is thicker than oceanic crust (6-8km)
        1. Oceanic crust (3.3) is denser than continental (2.7)
          1. Continental - made of granite
            1. Oceanic - made of basalt rock
      3. Lithosphere - uppermost layer of the earth(crust and solid top layer of the mantle)
        1. Asthenoshpere - the upper past of the earth's mantle, where the rocks are more fluid
        2. Convection currents
          1. 1. The core heats the molten rock in the mantle
            1. 2. Heated rock from the mantle rises to the earth's surface
              1. 3. At the surface the convection current moves the tectonic plates in the crust
                1. 4. Molten rock cools and flows back to the core to be reheated
          2. The core
            1. Made of Iron & Nickel
              1. Heat created by radioactive elements e.g uranium and thorium
                1. Outer is liquid. Inner is solid
            2. Plate tectonics
              1. Destructive plate Boundaries
                1. Example: Nazca and South American Plate
                  1. 2 plates collide and the denser basaltic oceanic plate is subducted under the lighter granitic continental plate
                    1. Many earthquakes and volcanoes
                2. Constructive plate boundaries
                  1. Example: Eurasian and North American plates
                    1. Rising convection currents pull oceanic crust apart forming volcanic ridge e.g. Miid-Atlantic ridge
                  2. Conservative plate boundaries
                    1. Example: San Andreas Fault, California
                      1. Two plates slide past each other - causes friction between plates - extreme stress build up in the crustal rocks
                        1. eventually released as an earthquake
                    2. Collision plate Boundary
                      1. Example:Indo-Australian and Eurasian plates
                        1. Two continental plates collide and the two plates buckle
                          1. Earthquakes are common
                            1. Buckling has led to fromation of the Himilayan chain
                      2. Aid for diasters
                        1. trained volunteers - clear debris
                          1. clean water - prevent disease spread
                            1. food
                              1. tents + blankets
                          2. radio communitcation
                            1. medical care
                              1. evacuation
                                1. refugees (forced to move due to natural hazard)
                            2. volcanoes
                              1. shield
                                1. found on constructive plate boundaries
                                  1. thin, runny lava
                                    1. Gentle sloping sides and a wide base
                                      1. basaltic magma - very hot - low silica and gas content
                                        1. erupt frequently but not violently
                                2. composite
                                  1. desrtuctive plate boundaries
                                    1. viscous, sticky lava and ash
                                      1. steep sloping sides and narrow base
                                        1. layers of thick lava and ash
                                          1. andesitic magma - less hot - silica and gas
                                            1. erupt infrequenly but violently, including pyroclastic flows (mix of gas, ash and rock)
                                  2. Montserrat, 1995
                                    1. Tiny caribbean island - 100km2
                                      1. volcano been dormant sice 17th century
                                        1. very viscous lava had blocked vent
                                        2. large amounts of ash, lava and pyroclastic flows
                                          1. Capital city, Plymouth covered in ash
                                            1. now become a 'ghost town' - services have relocated
                                          2. Impacts
                                            1. Effects
                                              1. social
                                                1. Population was10,500 now 5,000
                                                  1. had to permanently relocate to the north after inital evacuation by government for protection
                                                    1. some emigrated to Antigua and further afield (secondary)
                                                    2. economic
                                                      1. primary impact on econmy - devastating
                                                        1. agriculture and tourism
                                                          1. both have now slowly recovered
                                                            1. destruction of most of the island's crops (ash) - primary
                                                      2. primary - destruction of forests - fires ignited by the gas
                                                    3. Tsunami
                                                      1. triggered by earthquake/volcanic eruption happens at sea.
                                                        1. Movement of plates makes all of the water on top of this sea bed rise up
                                                          1. 2 blocks of water which move in opposite directions away from the epicentre, as huge waves
                                                      2. Impacts
                                                        1. Primary - those that take place at the time of the event itself and are directly caused by it
                                                          1. e.g. Road cracks, building collapse, landslides
                                                          2. Secondary - those that follow the vent in the hours, days and weeks after and are indirectly caused by it
                                                            1. e.g fires break out, disease spread and food/water run short
                                                          3. Earthquakes
                                                            1. Damage and loss of life
                                                              1. depends on - type of hazard, place's vulnerability to hazard, the capacity to cope and recover
                                                              2. Kashmir, 2005
                                                                1. Magnitude- 7.6 (richter scale) Epicentre - Muzaffarabad Death toll - 75,000
                                                                  1. Injured - 75,000 Homeless 2.8 million Property cost - $440 million
                                                                  2. Remote mountainous area
                                                                    1. Normal school day - many dead were children
                                                                      1. Ramadan - Many sleeping after waking for pre-dawn meal
                                                                      2. Primary - landslides, falling rock, large cracks in ground
                                                                        1. Secondary - Broken sewage pipes contaminated water supply and spread disease and people died of cold during harsh winter
                                                                          1. Impacts
                                                                          2. responses
                                                                            1. short term - the army/ emergency services, tents given out by charities, Aid workers form abroad to find surivors and treat injured
                                                                              1. long term - schools and hospital rebuilt, building regulations improved - reduce damage and death toll for future earthquakes
                                                                          3. How ready is San Francisco?
                                                                            1. Disaster waiting to happen
                                                                              1. Many faults threaten city
                                                                                1. San andreas and hayward - most dangerous
                                                                              2. costly to make old buildings safe
                                                                                1. Many buildings and critical structures in the city - not adaquately upgraded to withstand earthquakes e.g biggest hospital san francisco general, schools, bay bridge and the golden-gate bridge
                                                                                2. tension becuase city governement wants to reduce taxes and also be responsible
                                                                                3. Earthquake proof buildings
                                                                                  1. MEDC
                                                                                    1. More money to spend
                                                                                      1. pendulum - stop building sway
                                                                                        1. cross bracing - stop floor collapse
                                                                                          1. deep steel foundations - prevent collapse
                                                                                    2. LEDC
                                                                                      1. Need to use cheaper material e.g timber
                                                                                        1. cross braced bamboo frame
                                                                                          1. lightweight thatch roof not mud
                                                                                            1. steel rods foundation
                                                                                  2. Volcanoes
                                                                                    1. Prediction
                                                                                      1. Tiltmeters (detect when a volcano swells)
                                                                                        1. Boreholes (measure water temp.)
                                                                                          1. Aircraft (measures the gas)
                                                                                            1. Seismometers (measure tremors and earthquakes)
                                                                                              1. Hot springs are monitored
                                                                                      2. Protection
                                                                                        1. concrete shelters
                                                                                          1. evacuation routes clearly signposted
                                                                                            1. Concrete lahar channels divert dangerous mudflows
                                                                                              1. Insurance is udes so any damage can be fixed and repaired
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