tectonic hazards

• What is the plate tectonics theory?


  It states that the Earth's crust is divided into solid tectonic plates up to 100 km thick.
• How did plate tectonics theory develop?

  It developed from early world mapping of continents, mountain ranges, and volcanoes, along with fossil evidence, leading Alfred Wegener to propose that continents were once joined.
• Who suggested the idea that continents were once joined together?

  Alfred Wegener
• What mechanisms drive plate movements?

  Plate movements are driven by convection currents and gravitational sliding.
• How fast do tectonic plates move?

  Tectonic plates move between 2.5 to 35 cm a year.
• What happens at destructive convergent margins?

  Sinking convection currents coincide with destructive convergent margins where one plate subducts below another.
• What causes ridge push at divergent margins?

  Ridge push is caused by rising magma pushing the older part of the plate sideways.
• What is slab pull at subduction margins?

  Slab pull is caused by gravity pulling the thick, dense plate downwards.
• What are the two types of tectonic plates?

  • Oceanic crust: relatively recently formed, dense, thin
  • Continental crust: older, less dense, thicker, granitic
• What are the three types of plate margins?

  • Constructive margins: plates separate (diverge)
  • Destructive margins: plates collide (converge)
  • Conservative margins: plates slide past each other
• How are earthquakes measured?

  Richter scale