Earth and plate tectonic

• Plate Tectonics Theory


  A scientific theory that explains how major landforms are created as a result of Earth's subterranean movements

  
• The theory solidified in the 1960s and transformed the earth sciences by explaining many phenomena, including mountain building events, volcanoes, and earthquakes
• Earth's Layers


  • Core
  • Mantle
  • Crust

  
• Tectonic Plates


  Gigantic pieces of the Earth's crust and uppermost mantle, made up of oceanic crust and continental crust

  
• Tectonics


  Comes from the Greek word "tekton", meaning builder
• Convection


  Like a boiling pot, where heated soup rises to the surface, spreads and begins to cool, and then sinks back to the bottom of the pot where it is reheated and rises again
• Asthenosphere


  The hotter upper mantle below the lithospheric plate, can flow like silly putty, and is a viscoelastic solid, NOT liquid

  
• There are a dozen large lithospheric plates (smaller plates not shown), some have continents and some don't, and all are in motion

  
• Divergent Boundary


  Tectonic plates move apart from each other

  
• Oceanic-Oceanic Divergent Boundary

  • New oceanic crust is created to fill in the space as the plates move apart, located along mid-ocean oceanic ridges, with volcanic activity, shallow earthquake activity, and creation of new seafloor and a widening ocean basin

  
• Continental-Continental Divergent Boundary


  • Continental crust rifts or splits, creating a new ocean basin as the pieces of the continent move apart, with magma rising beneath the continent, causing it to become thinner, break, and ultimately split apart

  
• Convergent Boundary


  An area on Earth where two or more lithospheric plates collide, with one plate eventually sliding beneath the other in a process known as subduction

  
• Oceanic-Continental Convergent Boundary


  • The oceanic plate undergoes subduction and volcanic arcs arise on land, with the volcanoes releasing lava with chemical traces of the continental crust they rise through

  
• Oceanic-Oceanic Convergent Boundary


  • The denser plate sinks below the lighter plate and eventually forms dark, heavy, basaltic volcanic islands and trenches

  
• Continental-Continental Convergent Boundary


  • A continent or large island that has been moved along with subducting oceanic crust collides with another continent, creating mountain ranges like the Himalayas
• Transform Boundary


  Places where plates slide sideways past each other, with neither creation nor destruction of lithosphere, causing faults and earthquakes but no volcanoes

  
• Fault


  A place where there is a long break in the rock that forms the surface of the earth and where earthquakes are more likely to happen

  
• The Philippine Sea plate is tectonically unusual in that almost all the boundaries are convergent, with the Pacific plate subducting beneath the Philippine Sea plate to the east and the west/northwestern part of the Philippine Sea plate subducting beneath the continental Eurasian plate

  
• Being situated in the "Pacific Ring of Fire" makes the Philippines vulnerable to frequent earthquakes and volcanic eruptions, with an average of 20 typhoons every year, five of which are destructive
• There are thousands of small earthquakes every day, with "strong" earthquakes (~M7) occurring once a month and >M8 occurring about once per year
• Locations of volcanoes (ones above sea level) tend to occur along the plate boundaries
• Tectonic plates move 1-10 centimeters per year, about the rate of fingernail growth