MODULE 2

• Magma


  Molten rock found beneath the crust, contains different minerals
• Types of magma

  • Basaltic
  • Rhyolitic
  • Andesitic
• Basaltic magma


  • Rich in iron, magnesium, and calcium but low in potassium and sodium
  • Temperature ranges from 1000°C to 1200°C
  • Low viscosity and low gas content
  • Formed by dry partial melting
• Rhyolitic magma


  • Rich in potassium and sodium but low in iron, magnesium, and calcium
  • Temperature ranges from 650°C to 800°C
  • High viscosity and gas content
  • Formed by wet partial melting of the continental crust
• Andesitic magma


  • Moderate amount of present mineral
  • Temperature ranges from 800°C to 1000°C
  • Intermediate viscosity
  • Formed by wet partial melting of magma under the ocean
• Magma is composed of molten rocks, minerals such as iron, calcium, magnesium, silica and different gases such as water vapor, carbon dioxide, hydrogen sulfide, hydrochloric, and sulfuric acid
• Mafic magma


  Low in silica, contains magnesium iron and with low viscosity
• Felsic magma


  High in silica, contains minerals such as quarts and feldspar, and with high viscosity
• Viscosity


  Resistance of materials to flow
• Ways magma is formed

  1. Dry melting - melting of rocks and minerals without the presence of water and carbon dioxide

  2. Wet melting - melting of rocks and minerals with the presence of water occurring over varied temperature in the subduction zone
• Temperature


  Affects the flow of magma - high temperature has low viscosity, low temperature has high viscosity
• Magma is important to the Earth's surface
• Knowing the kind of magma emitted by volcanoes in the Philippines is important
• Mafic magma


  Magma that contains low silica
• Mafic magma moves

  Faster than Felsic magma
• Magma can be formed

  1. With the presence of water

  2. Without the presence of water
• The higher the temperature of magma


  The lower the viscosity and more gases are produced
• Knowing the kind of magma emitted by the volcanoes in the Philippines is important
• Basaltic magma


  Magma that has high content of Iron, Magnesium, and Calcium but low in Potassium and Sodium
• Statements that describe magma

  • The higher the temperature the higher the viscosity
  • The lower the silica the higher the viscosity
  • The Basaltic magma has a high temperature and low viscosity
  • The Rhyolitic magma has a low temperature and high gas period
• Rhyolitic magma


  Magma that has low gas content
• Factors that can affect the viscosity of magma

  • Silica content
  • Temperature
  • Gas content
  • Nickel content
• Felsic magma


  Magma that has high viscosity
• Potassium-rich magma


  A type of magma that is rich in potassium
• Rhyolitic magma


  Magma which has the highest viscosity and low temperature
• Viscosity


  Resistance to flow of magma
• Mafic igneous rock


  An igneous rock that contains less silica
• Andesitic magma


  Magma that has moderate amount of iron and silica
• The higher the temperature


  The lesser the viscosity
• Magma


  Made of molten rocks
• Basalt


  The igneous rock that contains high amount of silica and has dark color
• Felsic igneous rock


  The igneous rock that contains high amount of silica
• Characteristics of magma types

  • Basaltic
  • Rhyolitic
  • Andesitic
• Magma is involved in volcanic eruption, but its characteristics depend on viscosity, percentage of silica, mineral content, gas produce, and temperature
• Process of volcanic eruption

  1. Rocks near the mantle melts when magma is produced

  2. Magma becomes lighter and rises to the vent

  3. When magma rises or interacts with water, gases are formed

  4. The temperature and pressure increase inside the volcano

  5. Volcanic earthquakes are frequent and intensified, and more gases are emitted

  6. The magma flows on the fissure of the Earth's surface and crater
• Hydrothermal or Phreatic volcanic eruption is steam-driven as hot rock come in contact with water, produces ash without ejection of magma, and can bring magma fragment and crystals
• Phareatomagmatic volcanic eruption is violent as magma contacts with ground water, gas is compress within the magma, and results in large column of very fine ash and with ejection magma
• Strombolian volcanic eruption is the least violent explosive, with fountain lava about 1km and lava bomb
• Vulcanian volcanic eruption is moderate explosion of gas, with tall eruption columns up to 20 km high, pyroclastic flow, ashfall tephra, and dense cloud of ash
• Pelean volcanic eruption involves large quantity of gas dust and ash, pyroclastic flow, and dense lava rolls down the volcano at high speed