Restless Earth

Restless Earth

1. Structure of the Earth

   • Crust- A very thin layer, divided into plates
   • Upper Mantle- Solid because it's closer to the surface of the Earth it's cooler
   • Lithosphere is Mantle and Crust. Below the Lithosphere is very viscous
   • Asthenosphere is Upper Mantle
   • Core is Iron and Nickel. Generates magnetic field
   • Inner core is solid because of pressure
   • Oceanic more dense, thicker with Basaltic rocks.
   • Continental less dense, thinner with Continental rocks

2. Plates

   • Permian (Pangea) 225 million years ago
   • Triassic (Laurasia, Gondwanaland) 200 million years ago
   • Laurasia Continents Asia, North America, Europe
   • Constructive in seas
   • Destructive on land
   • Conservative are random
   • Constructive (Divergent)- Plates pull apart
   • Destructive (Convergent)- Plates push together and one subducts
   • Collision- Plates push towards each other
   • Conservative- Plates slide past each other

3. Volcanoes

   • Landform erupting lava through a fissure in crust
   • Measured on Volcanic Explosivity Index (VEI)
   • Andesitic Magma- Lower temp, high number dissolved gases, high silica content
   • Basaltic Magma- Higher temp, low dissolved gases, low silica
   • High viscosity- Explosive!
   • Shield Volcano- Found at conservative, basaltic lava, not explosive
   • Strato Volcano- Found at destructive, andesitic lava, explosive!
   • Prediction- Tilt meters, monitoring gases
   • Planning (Evacuation, drills, safe zones)
   • Education (warning signs, hazards, evacuation routes)

4. Earthquakes

   • Shaking of Earth's crust, due to movement of Earth's plates
   • Plates get stuck, pressure build up. When released an earthquake occurs
   • Releases seismic waves
   • Focus is inside the crust where pressure is released. Epicentre is point on Earth's surface above the focus
   • LEDC protection- Steel rod foundations, cross braced wood or bamboo frames, concrete rings tie walls to foundation
   • MEDC protection- Cross bracing, tuned mass damper, base isolators

5. Tsunamis

   • Triggered by earthquake in the sea, displaces water
   • MEDCs- Warning systems
   • Reach heights of 30m at shore!
   • At Sea- Small Shore- Big

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