Science

• Geothermal energy is a type of renewable energy taken from the Earth's core
• Geothermal energy comes from heat generated during the original formation of the planet and the radioactive decay of materials
• The thermal energy is stored in rocks and fluids in the center of the earth
• The four layers of the Earth are:

  • Inner core
  • Outer core
  • Mantle
  • Crust
• Geothermal reservoirs can be found in areas with:

  • Geysers
  • Boiling mud pots
  • Volcanoes
  • Hot springs
• Heat energy can be brought to the Earth's surface by:

  • Directly from hot springs/geysers
  • Geothermal heat pump
  • Direct use
  • Indirect use
• Geothermal power plants use steam from reservoirs of hot water found below the Earth's surface to produce electricity
• Geothermal energy is considered efficient, sustainable, clean, reliable, and renewable
• Geothermal energy will last until the Earth is destroyed by the sun in around 5 billion years
• Direct uses of geothermal energy include:

  • Hot springs used as spas
  • Heating water at fish farms
  • Providing heat for buildings
  • Raising plants in greenhouses
  • Drying crops
  • Providing heat to industrial processes
• Indirect use of geothermal energy includes electricity generation
• Advantages of using geothermal energy:

  • Does not produce pollution or contribute to the greenhouse effect
  • Power stations do not take up much room
  • No fuel is needed
  • Energy is almost free
• Disadvantages of using geothermal energy:

  • Limited places to build geothermal power stations
  • Need hot rocks of a suitable type at a drillable depth
  • Geothermal sites may "run out of steam"
  • Hazardous gases and minerals may come up from underground
• A volcano is an opening in the Earth's surface where molten rocks, smoke, gases, and ashes are erupted
• Inactive volcanoes are those that have not erupted for the last 10,000 years and their physical form is being changed by agents of weathering and erosion through the formation of deep and long gullies
• Active volcanoes are those that have a record of eruption within the last 600 years or those that erupted 10,000 years ago based on analyses of its materials
• Primary factors affecting the volcanoes' eruptive style include:

  • The magma's temperature
  • Its chemical composition
  • The amount of dissolved gases it contains
• Types of volcanic eruptions:

  • Phreatic or hydrothermal: a stream-driven eruption characterized by ash columns, may be an onset for a larger eruption
  • Phreatomagmatic: a violent eruption due to the contact between water and magma, resulting in a large column of very fine ash and high-speed emission of pyroclastics called base surges
  • Strombolian: a periodic weak to violent eruption characterized by fountain lava
  • Vulcanian: characterized by tall eruption columns reaching up to 20 km high with pyroclastic flow and ashfall tephra
• • Plinian: excessively explosive eruption of gas and pyroclastics
• The three volcanic cones are Shield Volcanoes, Cinder Cone, and Composite Cone
• Volcanic eruptions affect society negatively by causing loss of lives and properties, but they can also have positive effects
• Signs of an impending volcanic eruption include:

  • Increase in the frequency of volcanic quakes with rumbling sounds
  • Occurrence of volcanic tremors
  • Increased steaming activity
  • Change in color of steam emission from white to gray due to entrained ash
  • Crater glow due to the presence of magma at or near the crater
  • Ground swells, ground tilt, and ground fissuring due to magma intrusion
  • Localized landslides, rockfalls, and landslides from the summit area
  • Noticeable increase in the extent of drying up of vegetation around the volcano's upper slopes
• • Increase in the temperature of hot springs, wells, and crater lake near the volcano
  • Noticeable variation in the chemical content of springs, crater lakes within the vicinity of the volcano
  • Drying up of springs/wells around the volcano
  • Development of new thermal areas and/or reactivation of old ones; appearance of solfataras
• Viscosity is the property of materials resistance to flow. It is also described as a fluid thickness and stickiness.
• Lava with less silica content has low viscosity, allowing it to travel a great distance and form a thin sheet
• Lava with high silica content is too viscous to travel far and tends to break up as it flows
• Lava with low amount of gas and high silica content is very viscous and does not flow out as it rises, forming a columnar plug in the vent
• Lava with low amount of gas as it rises has high viscosity, causing it to pile up at a vent and result in a dome