types of volcano and classification of erruptions

• Types of volcanoes:
• Cinder cones (scoria):

  • Simplest and common type of volcano
  • Sharp conical hill constructed atop a vent, largely made of basalt
  • Smaller than shield and composite volcanoes
  • Have a crater at the summit and steep sides
• Composite volcanoes (stratovolcano):

  • Alternating layers of pyroclastic materials and hardened lava flow, felsic to intermediate rocks
  • Explosive with symmetrical slope and intermediate steepness
• Shield volcanoes:

  • Broad, gently sloping landform made of layers of low-viscous lava flows
  • Found at spreading centers and intraplate hotspots
  • Not steep and non-explosive
• Volcanic domes (lava domes):

  • Rounded, steep-sided mound made of bulging masses of dacite and rhyolite
  • Formed when lava reaching the earth is too viscous to flow away and accumulates around the vent
  • Characterized by long periods, hybrid seismicity, and shallow depth
• Supervolcano:

  • Largest eruptions and most dangerous type of volcano
• Submarine volcanoes:

  • Magma erupts in underwater fissures or vents in the earth's surface
• Subglacial volcanoes (glacial volcanoes):

  • Volcanic form produced by subglacial eruption beneath the glacier or ice sheet
  • Melted into a lake by rising lava
• Magmatic eruptions can be classified into different types:

  • Icelandic
  • Hawaiian
  • Strombolian
  • Vulcanian
  • Pelean
  • Plinian
• Icelandic eruptions involve effusions of molten basaltic lava that flow from long, parallel fissures
• Hawaiian eruptions are the calmest and involve non-explosive eruption of gusher-like lava fountain that generates red hot lava rivers of very fluid basaltic lavas in summit and fissure vents
• Strombolian eruptions involve mild blasts and bursting of gas bubbles within magma, leading to the ejection of incandescent cinders, lapilli, and lava bombs
• Vulcanian eruptions produce a dense cloud of ash-laden gas from the crater, reaching high above the peak. Entrapped gases in viscous lava are sufficient to blow the overlying crust of solidified lava
• Plinian eruptions are the most explosive and powerful of all eruptions
• Pelean eruptions involve large quantities of gas, ash, dust, and lava blown out of the volcano's central crater. They generate explosive outbursts that produce pyroclastic flows, dense mixtures of volcanic fragments, and gas
• Phreatomagmatic eruptions can be classified into:

  • Surtseyan
  • Submarine
  • Subglacial
• Surtseyan eruptions are hydromagmatic eruptions where magma interacts with shallow groundwater or surface water
• Submarine eruptions occur beneath the surface water
• Subglacial eruptions involve glaciovolcanism between ice and lava under the glacier
• Phreatic eruptions, also known as stream-blast eruptions, occur when water beneath or on the surface is heated by volcanic activity, leading to a cold ground or surface water contact with hot rock or magma