Volcanoes

• Volcano


  A rupture in the Earth's crust through which molten rock, volcanic ash, and gases escape from the Earth's mantle. This can occur in various forms, including through fissures, vents, and cones. The word "volcano" originates from Vulcan, the Roman god of fire.
• The Ring of Fire is a region in the Pacific Ocean known for what geological feature called volcanoes
• The largest volcano in the solar system is located on planet Mars
• Parts of a Volcano

  • Magma Chamber
  • Vent
  • Crater
  • Cone
  • Sill & Dike
  • Secondary Vents/Cones (Parasitic Cones)
  • Fissures
  • Lava Flow & Pyroclastic Flow
• Magma Chamber


  The area within the Earth where magma is stored before an eruption. It is located beneath the volcano.
• Vent


  The main outlet for the magma to escape. It is a tube-like structure that extends from the magma chamber to the surface of the volcano.
• Crater


  The opening at the top of the volcano where an eruption takes place. It is usually a bowl-shaped depression formed by the collapse of land following an eruption.
• Cone


  The mound or hill that builds up around the vent. The shape and size of the cone can vary depending on the type of eruption and the materials ejected.
• Sill & Dike


  Pathways that magma uses to reach the surface. A sill is a horizontal pathway, while a dike is a vertical or diagonal pathway.
• Secondary Vents/Cones (Parasitic Cones)


  Additional outlets for magma. They can form on the sides of the volcano and can have their own craters.
• Fissures


  The openings in a volcano through which lava flows
• Lava Flow & Pyroclastic Flow

  Lava flows are streams of molten rock that pour or ooze from the vent during an eruption. Pyroclastic flows are fast-moving currents of hot gas and volcanic matter.
• Types of Volcanoes


  • Shield Volcanoes
  • Stratovolcanoes (Composite Volcanoes)
  • Cinder Cone Volcanoes
• Shield Volcanoes


  Broad, gently sloping volcanoes built from fluid basaltic lava
• Shield Volcanoes


  • Mauna Loa in Hawaii
• Stratovolcanoes (Composite Volcanoes)


  Tall, steep-sided volcanoes built from alternating layers of lava flows, volcanic ash, and other volcanic debris
• Stratovolcanoes (Composite Volcanoes)


  • Mount Fuji in Japan, Mount St. Helens in the USA
• Cinder Cone Volcanoes


  Small, steep-sided volcanoes built from pyroclastic fragments
• Cinder Cone Volcanoes


  • Parícutin in Mexico
• Calderas


  Large, basin-shaped depressions formed by the collapse of a volcano after a massive eruption
• Calderas


  • Yellowstone Caldera in the USA
• How Do Volcanoes Form?

  Volcanoes form due to the movement of tectonic plates. The Earth's outer shell, known as the lithosphere, is divided into several large and small plates. These plates move relative to each other, and when they interact, they can create conditions favorable for volcanic activity.
• Convergent Plate Boundaries


  When two plates collide, one plate can be forced beneath the other in a process known as subduction. This can lead to the melting of rock and the formation of magma, which can eventually erupt as a volcano.
• Divergent plate Boundaries


  When two plates move away from each other, magma from the mantle rises to fill the gap, leading to the formation of new crust and volcanic activity.
• Hotspots


  Areas of intense volcanic activity that are not necessarily located at plate boundaries. A hotspot is a plume of hot mantle material that rises through the Earth's crust, creating volcanoes as the overlying plate moves over it.
• Factors that influence the nature of a volcanic eruption

  • Magma Composition
  • Gas Content
  • Tectonic Setting
• Magma Composition


  The type of magma (basaltic, andesitic, or rhyolitic) can determine the viscosity and explosiveness of the eruption.
• Gas Content


  The amount and type of gases (water vapor, carbon dioxide, sulfur dioxide) dissolved in the magma can influence the explosiveness of an eruption.
• Tectonic Setting


  The geological setting, such as convergent boundaries, divergent boundaries, or hotspots, can also affect the style of volcanic eruption.
• Volcanic Hazards


  • Lava Flows
  • Pyroclastic Flows
  • Ashfall
  • Lahars
• Lava Flows


  Streams of molten rock that can destroy everything in their path.
• Pyroclastic Flows


  Fast-moving currents of hot gas and volcanic debris that can travel at high speeds, engulfing and incinerating everything in their way.
• Ashfall


  Volcanic ash can blanket large areas, disrupting transportation, damaging infrastructure, and posing respiratory hazards.
• Lahars


  Volcanic mudflows composed of water, volcanic ash, and debris, often triggered by heavy rainfall or the melting of snow and ice during an eruption.
• Tephra


  The hardened remains of lava that once flowed from a volcano.
• Lahar


  Volcanic hazard consists of a fast-moving mudflow containing water and volcanic material.
• Feldspar is the most abundant mineral in volcanic rock.
• Dormant Volcano


  A type of volcano that is not currently erupting but may erupt again in the future.
• Types of Volcanic Eruptions

  • Hawaiian Eruptions
  • Plinian Eruptions
  • Vulcanian Eruptions
  • Strombolian Eruptions
  • Effusive Eruptions
  • Explosive Eruptions
• Hawaiian Eruptions


  Eruptions characterized by effusive eruptions of very fluid basaltic lava that flows easily to form shield volcanoes. They can also produce fire fountains from the vent.