Volcanoes

• Describe a volcano structure

  Cone-shaped structure with a central vent or pipe that links the Earth’s interior to the surface.
• How is a volcano formed?

  When there is a weakness in the Earth’s crust where magma can escape from the mantle
• Another word for molten rock is


  Magma
• What is lava


  When magma reaches the earth‘s surface
• Volcanos and Earthquakes are found near the boundaries of continental plates. When one plate slides beneath another magma can reach the surface.
• Where are volcanoes found

  in hot and cold regions.
• Can volcanoes be found in sea?

  Yes, on the seabed.
• Cone-shaped structure


  The visible part of the volcano that we see above ground. Formed by the accumulation of magma, ash, and rock debris expelled by the volcano during eruptions.
• Magma chamber


  A large pool of molten rock that feeds the volcano with magma, located several kilometers beneath the volcano's surface.
• Central vent or pipe


  The opening through which magma, ash, and volcanic gases escape from the Earth's interior to the surface, connecting to a magma chamber located beneath the volcano.
• Lava flows


  Solidified streams of molten rock that flow down the slopes of the volcano during an eruption.
• How does a volcano look


  A cone-shaped structure with a vent/pipe
• Archipelagoes 


  volcanoes that form chains of islands
• Tephra


  Solid materials/ bombs ejected from volcano
• Tuff


  Ash and dust
• Lapilli


  Small rock fragments
• Lahar


  Volcanic ash and water moving downhill/mudflow
• Types of volcanic material

  • Ash
  • Cinders
  • Debris
  • Minor vent
  • Cone
  • Major vent
  • New crater
  • Rim
• Subsidiary


  Minor vent
• Vent eruption


  Blown off by
• Shield volcanoes


  • Formed from basic lava
  • Non-violent, as volcanic gases escape quite easily from the vent
  • Sides of the cone are gentle and consist of ash and cinder
• Shield volcanoes


  • Mauna Loa
  • Mauna Kea
• Strombolian volcanoes


  • Produce ash, cinders and volcanic bombs which are hurled into the air
  • Acidic lava forms steep-sided cone-shaped volcanoes
  • Red-hot ash and gas, known as nuee ardente, pour from the vent, destroying everything in their path
• Strombolian volcanoes


  • Paricutín
  • Smaller types in Nevis
• Composite cones


  • Flat-based steep-sided cones consisting of alternate thick layers of ash and cinders and viscous lava
  • Lava often escapes from the sides of the cone, building up small cones or conelets
• Composite cones


  • Fujiyama
• Caldera formation


  1. Central part of the crater of a composite cone is blown away by an explosion

  2. Top of the volcano slowly subsides into the underlying magma chamber

  3. Circular depression or crater known as a caldera is formed in the remains of the volcano
• Magma


  Molten rock in a semi-liquified state deep inside the Earth
• Lava


  Molten rock on the Earth's surface
• Basic/fluid lava


  • Builds up gentle-sided cones
  • Thin and runny, flowing for several kilometres before solidifying
• Acidic lava


  • Cools quickly around the vent
  • Forms steep-sided cones
• Acidic lava


  • Mount Soufrière in St Vincent
• Crater lakes


  • Gran Étang and Lake Antoine in Grenada
• Volcanic plug or neck formation

  1. Vent of a volcano becomes blocked with thick, viscous lava

  2. Cone is gradually eroded away

  3. Plug or neck stands as a pinnacle in the vent or pipe
• Volcanic plugs or necks

  • Gros Piton and Petit Piton in St Lucia
• The Pitons, St Lucia


  • Volcanic plugs or necks
  • Gros Piton (800 m)
  • Petit Piton (710 m)
  • Both peaks can be climbed
• Volcanic tourist attractions


  • Hot or thermal springs at Bath, St Thomas and Milk River, Jamaica
  • Spas developed around the springs
  • Famous for medicinal properties
• Volcanic features


  • Fumaroles or solfataras in the Valley of Ten Thousand Smokes in Alaska, Valley of Desolation in Dominica, and Sulphur Springs at Soufrière in St Lucia
  • Geysers in Yellowstone National Park, USA, including Old Faithful
• Vulcanologist


  A person who studies volcanoes, watching, recording and interpreting their activity
• What vulcanologists look out for

  • Likelihood of eruptions can be predicted with seismographs, tiltmeters, gas emissions, and bulges in the Earth's surface