sci lesson 2: volcanic eruption

• Mt. Pinatubo one of the composite volcanoes that constitute the luzon volcanic arc erupted in june 1991
• PHIVOLCS MEANING- Philippine institute of volcanology and seismology
• volcanic process refers to the eruptive and non-eruptive activities
• vesicles: gas bubbles
• tephra: volcanic gases in the magma expand and break magma into tiny pieces
• viscosity: dtermines how easily gas escapes in the atmosphere
• viscosity depends on 3 factors

  1. silica
  2. temperature of the lava
  3. gas dissolved in magma
• pyroclastic flows are mostly observed during volcanic eruption and are a mixture of hot gases and solid fragments
• intrusive igneous rocks are magma trapped beneath the surface that cools and solidifies into coarse-grained materials
• 2 types of volcanic eruption

  1. explosive eruption
  2. effusive eruption
• explosive eruption characterized by gas-driven explosion
• effusive eruptions feature the outpouring of lava without significant explosive eruption
• 3 metatypes fo eruption

  1. magmatic
  2. phreatomagmatic
  3. phreatic
• MAGMATIC ERUPTIONS

  1. hawaiian
  2. strombolian
  3. vulcanian
  4. pelean
  5. plinian
• PHREATOMAGMATIC ERUPTIONS

  1. surtseyan
  2. submarine
  3. subglacial eruption
• PHREATIC ERUPTION

  also called steam-blast eruption
• hawaiian- named after the kilauea vulcano on the big island of hawaii
• hawaiian are fire fountains
• hawaiian is the calmest eruption type
• strombolian- bursting of gas bubbles
• large bubbles called gas slugs
• vulcanian - named after the italian islan Vulcano which is also belived to be the home to the greek god of fire, hephaestus
• vulcanian occurs when the pressure of entrapped gases in a relatively viscous magma becomes sufficient
• pelean also called nuee ardente eruption
• pelean occurs when a large quantity of gas, dust, ash and lava fragments are blown out of a volcanos central craters
• pelean is the most dangerous volcanic activities in the world
• plinian is the most explosive and powerful of all eruptions
• surtseyan - named after the island of surtsey off the coast of iceland
• surtseyan kind of hydromagmatic eruption where magma interacts explosively with shallow ground water
• surtseyan occurs when sn undersea volcano has finally matured enough
• submarine type of volcanic eruption that takes place beneath the surface of water
• submarine is generated at subduction zones
• subglacial volcano: also called as glaciovolcanism
• subglacial volcano features the interaction between lava and ice often under a glacier
• subglacial volcano occurs at aras of high latitude
• two factors of subglacial volcano : glacier and active volcano
• phreatic eruptions those driven by explosive expanding steam resulting from cold ground
• tilt-meter: to measure the expansion of a volcano
• Seismometers: installed to record the motion of the ground during an earthquake
• thermometers to check the temperature of the surrounding area