Grade 9 Earth & Space

• Vulcan Point is one of the cones of the active Taal volcano
• The Philippines is known for its diverse natural resources and scenic views like mountains and volcanoes
• The Philippines is situated in the Pacific Ring of Fire, which is characterized by frequent earthquakes and volcanic eruptions
• Volcanism


  A phenomenon connected with volcanoes and its volcanic activity
• Volcano


  A mountain that opens downward to a pool of molten rock below the surface of the earth
• Magma


  Hot liquid rock under the earth's surface
• Lava


  Magma that has erupted through the earth's surface
• Formation of volcanoes


  1. Melted crust

  2. Subduction

  3. Underwater volcanoes

  4. Hot spot volcanoes
• Types of volcanoes by shape

  • Cinder cone
  • Composite
  • Shield
  • Lava dome
• Classification of volcanoes by PHIVOLCS


  • Active erupting
  • Active dormant
  • Inactive
• The Philippines has more than 100 volcanoes as of 2013
• Advantages and disadvantages of living near volcanoes

  • Destruction risk
  • Volcanic materials important for human life
  • Attract tourism
• Volcanism is a phenomenon connected with volcanoes and its volcanic activity
• Magma


  Semi-liquid rock crystallized minerals dissolved gases and extremely hot liquid formed and found beneath the surface of the earth
• Much of the earth's mantle is made largely of magma
• Volcanic eruption


  1. Magma pushes through holes or cracks in the crust

  2. Magma is ejected out of the volcano as lava

  3. Lava cools and solidifies into igneous rocks
• Temperature of magma


  Ranges from 700 to 1300 degrees celsius
• Factors affecting volcanic eruption

  • Magma's temperature
  • Magma's chemical composition
  • Amount of dissolved gases in magma
• Viscosity


  Property of the material's resistance to flow, also described as the liquid's thickness and stickiness
• Temperature of magma


  Viscosity of magma decreases as temperature increases
• Silica content in magma

  Magmas with high silica content are more viscous than those with low silica content
• Gases dissolved in magma

  Tend to increase magma's ability to flow
• Loss of gases in near-surface environments

  Makes magma more viscous, forming a dome or a columnar
• Volcanic eruption process


  1. Magma is continuously heated

  2. Gas bubbles develop and expand, increasing pressure

  3. Pressure exceeds strength of overlying rock, causing fracturing

  4. Magma is ejected out as lava
• Types of volcanic eruptions


  • Icelandic
  • Hawaiian
  • Strombolian
  • Vulcanian
  • Plinian
  • Peleean
• Icelandic eruption


  • Effusions of molten basaltic lava that flow from long parallel fissures, often building lava plateaus
• Hawaiian eruption


  • Fluid lava flows from a volcano summit and radial fissures to form shield volcanoes with gentle slopes
• Strombolian eruption


  • Moderate bursts of expanding gases that eject clots of incandescent lava in cyclical or nearly continuous small eruptions
• Vulcanian eruption


  • Moderate explosions of gas laden with volcanic ash, forming dark turbulent eruption clouds that rapidly ascend and expand
• Peleean eruption


  • Explosive outbursts that generate pyroclastic flows, dense mixtures of hot volcanic fragments and gas that pour down valleys and slopes at great velocities
• Plinian eruption


  • Intensely violent, with gases boiling out of gas-rich magma generating enormous and nearly continuous jetting blasts that core out the magma conduit and rip it apart
• Volcanic emissions


  • Volcanic bombs
  • Eruption clouds
  • Tephra
  • Eruption columns
  • Pyroclastic flows
  • Lahars
  • Lava flows
• Volcanic eruptions help bring out various minerals and chemicals to the surface, increasing soil fertility
• Volcanic ash is valued as a premium building and construction material
• Volcanic eruptions can result in widespread damage, destroying cities and infrastructure, causing loss of lives and properties
• Volcanic eruptions can impact the local flora and fauna due to ash and toxic gases
• Climate change is a natural phenomenon and has been occurring since the earth came into being
• Climate change is a change in the average weather of a given area or region
• The earth goes through periods of cooling and warming
• The increase of earth's temperature is a natural occurrence caused by natural processes