Plate Tectonics

Birth of the Earth

  • Dust → Ring → Small protoplanets smashed together, made Earth, smashing made it really hot, which is why Earth has the inner hotness

    • Because it’s liquid and inner is hotter, we have convective flow, heat up and move around

    • Crust is where nondense rock floats into, and far enough so that it’s solid

    • Mantle is also rock, but has metals (iron, magnesium), which gives it some properties. Rigid, top is plastic (moldable), where most convective flow happens.

    • Core is all metal, where all the hot stuff is. Nickle, iron, and other super dense things all the way down. Only purpose in plate tectonics is making things move because it’s really hot, fully liquid portion and solid portion (because too much pressure so it can’t melt).

Plate Tectonics

  • Causes are convective flow and top of mantel is plastic

  • Continental crust is thicker and less dense

  • Oceanic crust is significantly thinner and more dense

Tectonic Plate Boundaries

  • Interactions of the border between two tectonic plates

  • Transform Boundary: Two tectonic plates are sliding past each other, no creation or destruction, just moving onwards on conveyor belt

    • Fault lines

    • Earthquakes, ranges in strength depending on tension and strength

  • Divergent Boundary: Two tectonic plates moving away from each other, beginning of conveyor belt, magma turns into rock → lithosphere, new plates

    • Rift valleys (Midatlantic Ridge), volcanoes, small & shallow earthquakes

    • Iceland & East Africa Rift Valley

    • Under the ocean, seafloor spreading

    • Where seafloor is young

  • Convergent Boundary: End of conveyor belt where you die, destruction of tectonic plates because of two tectonic plates moving towards each other

    • Only nonnormal transformation, composition density & size of tectonic plates (most different due to type of crust, continental vs oceanic)

    • Mountain ranges

    • Volcanoes

    • Underwater trenches

    • Underwater mountains, creates islands

    • Not enough friction when subduction happens, really deep and strong earthquakes, 80% of earthquakes happen at convergent boundaries

    • Japanese Island Arc, Andes Mountains, Himalayan Mountains

  • Subduction Zones: Where crust forced down and starts melting, material will rise due to low density and high temperature, resulting in volcano or island formation

    Discover Subduction Zones

Importance

  • Earthquakes

  • Ring of Fire: Volcanoes, around super active plate tectonics

Earthquake Formation

  • When energy stored up because of friction between 2 plates

    • Side-by-side or convergent spring in upwards

    • Energy stored determines strength of earthquake

  • In Transform Boundaries, tectonic plates are stuck, then huge amount of energy is released at once which causes earthquakes

  • Tsunamis: Underwater earthquakes, worse at convergent because of vertical displacement, a lot of water moving up at once because of high energy activity

    • Earthquake pushes land up, makes water go up

    • Can also happen at transform boundary, creates underwater landslide which moves a lot of water

    • Usually at convergent boundaries

Tsunami Information | Seismic Safety Commission

Describe: 1-2 sentences, provide relevant characteristics (what it looks like, how it works)

Explain: 1-2 sentences, cause & effect, big emphasis on why something happens with evidence and reasoning

  • Ecological: animal/nature

  • Social: Welfare (diseases, food, shelter)

  • Economic: money/businesses