Earth and Science

• Seismic waves


  Energy radiates in all directions from the focus in the form of waves, which are recorded in Seismographs
• Earthquake


  Vibration of the earth produced by the rapid release of energy most often because of the slippage along a fault in the earth's crust
• Types of Seismic waves

  • Surface Wave
  • Body wave
• Surface waves


  • Can only travel through the surface of the earth
  • Have two subtypes: Love wave and Rayleigh wave
• Love wave


  Named after A.E.H Love<|>Faster than Rayleigh wave<|>Moves the ground in a side to side horizontal motion<|>Cause the most damage to structures
• Rayleigh wave


  Named after Lord Rayleigh<|>Rolls along the ground just like water waves
• Body waves


  • Can travel through the earth's inner layers
  • Used by scientists to study the earth's interior
  • Have two subtypes: Primary wave and Secondary wave
• Primary (P) wave


  Travel faster than Secondary waveAlso called Compressional wave<|>Quickly travels through earth and liquid
• Secondary (S) wave


  Travel slower than a P wave<|>Move as shear or transverse waves<|>Force the ground to sway from side to side
• Layers of the Earth

  • Crust
  • Mantle
  • Core
• Mantle


  • Beneath the crust
  • Extends to about 2,900 km
  • Makes up about 80% of the Earth's total volume
  • Made up of silicate rocks
  • Lower mantle is denser than the upper mantle
  • The lower part of mantle consist of more iron than the upper part
  • High temperature and pressure
• Core


  • Subdivided into two layers: the inner core and outer core
• Crust


  • Thinnest and outermost layer of the Earth
  • Subdivided into two regions: Continental and Oceanic Crust
• Continental Crust


  • Mainly made up of Silicon, Oxygen, Aluminum, Calcium, Sodium and Potassium
  • The thickness is mostly 35-40 km
  • Found under land masses
  • Made of less dense rocks such as granite
• Outer core

  • 2,250 km thick and made up of iron and nickel
  • Temperature in the outer core reaches up to 2000°C
• Inner core


  • Made up of solid iron and nickel has a radius of 1,300 km
  • Temperature reaches to about 5000°C
• Oceanic Crust


  • 7-10 km thick with an average thickness of 8 km
  • Found under ocean floor
  • Made of dense rock such as basalt
  • Heavier than continental crust
• Plate Boundaries

  • Divergent
  • Convergent
  • Transform Fault
• Converging oceanic crust leading plate and continental leading plate

  1. Oceanic crust undergoes subduction process or the bending of the crust towards the mantle

  2. The subducted crust melts forming magma

  3. Volatile material such as water causes magma to become less dense, rise and reach the crust once again causing volcanic activities on the continental leading plate
• Ocean trenches


  • The deepest part of the ocean, Philippine trench is one of the deepest trench with a depth of 10,540 meters
• Tsunami


  Japanese word for "harbor wave"<|>Series of ocean waves with very long wavelength<|>Caused by large scale disturbances of the ocean
• Volcanic Island Arc


  Chain of volcanoes positioned in an arc shape<|>Formed by converging plates
• Plate Boundary Types and Features

  • Oceanic - Oceanic = Volcanic island, Trenches, Earthquake
  • Oceanic - Continental = Volcanic Island Arc, Trenches, Earthquake
  • Continental - Continental = Earthquake, Mountain Ranges
• Diverging Plate Boundaries

  • Oceanic - Oceanic = Ocean ridges
  • Continental - Continental = Rift valleys
• Continental Jigsaw Puzzle


  Evidence that the continents were once one large landmass called Pangaea
• Alfred Wegener proposed the theory that about 200 million years ago the continents were once one large landmass called "Pangaea"
• Evidence for Continental Drift Theory


  • The apparent fit of the continents
  • Fossil correlation
  • Rock and Mountain correlation
  • Paleoclimate data (Past climate data)
• Sea Floor Spreading

  Oceans are flat and spreading apart, showing that continental drift and plate tectonics are true phenomena
• Convection current


  Hot less dense particles cool down, sink, and other less dense particles rise
• Magnetic Reversal


  Also called magnetic flip of the earth, when the north pole is transformed into south
• Ridge Push


  As the older seafloor sinks, the weight of the uplifted ridge pushes the oceanic crust towards the trench at the subduction zone
• Slab Pull


  The weight of the subducting plate pulls the trailing slab into the subduction zone