drrr lesson 5

• Volcano

  are opening in the Earth's crust that allows energy from the interior of the Earth to escape to the surface. The energy in the magma that goes out are in the form of lava, ash, and gas
• How volcanoes are formed?

  subduction allows water from the subducting plate to be driven upward, off the subducting plate and into the mantle wedge
• 2 ways magma escape

  1. Intrusion
  2. Extrusion
• Intrusion

  • "inside" internal magma pulls down the volcano
  • the creation of sedimentary rocks 
• Extrusion

  • "outside" external flow of magma
  • forms igneous rocks
• molten rock


  magma
• Classifications of Volcano

  1. Active Volcano
  2. Dormant Volcano
  3. Extinct Volcano
• Active volcano 


  erupts regularly

  ex: taal volcano 
• Dormant Volcano

  tendency to erupt in the future

  ex: Mount Fuji
• Extinct volcano


  have not erupted in human history and does not have magma
• Dormant can be active if heat is sufficient
• Potential hazard of volcano


  Volcanic hazard
• Types of Volcanoes

  1. Stratovolcanoes
  2. Shield Volcano
  3. Calderas
  4. Mid-Ocean Ridges
• Stratovolcanoes 


  -appear as tall steep mountains

  -perfect triangular shape
• Shield Volcano

  flatter and dome shaped that produces low viscosity, runny lava, it spreads from the source
•  Calderas

   -large depressions in the ground -has a deep crater
• Mid-Ocean Ridges 


  -underwater chains of volcanic mountains

  -can be found at the Pacific ocean
• Volcanic Hazards


  any potentially dangerous volcanic process that puts human lives, livelihood or infrastructure at risk of harm
• Potential volcano-related hazards

  1. Lahar
  2. Ash fall
  3. Pyroclastic flow
  4. Ballistic Projectile
  5. Volcanic Gas
  6. Lava flow
• Lahar 


  -is a mixture of water, pyroclastic materials and rock fragments flowing down a volcano or river valley

  -type of mudflow or debris flow
• Pyroclastic materials 


  cinder, ash, volcanic bomb
• Ash fall 


  -composed of bits and pieces of pulverized rock, minerals, and volcanic gloss generated from the volcanic eruption

  -can cause larger impact and wider casualties. -it lasts up to months

  -affects air visibility which means it could cause plane turbulence
• Pyroclastic flow 


  refers to hot dry masses of fragmented volcanic materials that move along the slope in contact with ground surface

  -hot & dry = faster and wider casualties. 
• Ballistic Projectile 


  is a rock fragment that is ejected from the volcano during its explosive eruption. It is like a cannonball that travels fast in the air 
• Volcanic Gas 


  -gases given off by active volcanoes, consists of sulfur diovide and hydrogen sulfide, which are poisonous and hazardous to organisms

  -too much inhalation could cause respiratory problems
• Signs of an impending volcanic eruption


  • Occurrence or increase in the frequency of small earthquakes
  • Deformation in the ground manifested by changes in ground elevation (tilting) and formation of cracks or openings (ground fissuring)
  • Increase in the amount of volcanic gases and in temperature, which may indicate that the magma has gone closer to the surface
  • Glow of volcanic crater due to the presence of magma
  • Increase in steam emissions coming from volcanic openings, fissures, or hot springs
  • Thermal changes within the surroundings of the volcano
  • Change in the color of nearby vegetation and lakes
  • Landslides and rockfall not due to heavy rains
  • Drying up of springs and fresh water sources around the volcano
• Parameters used to monitor volcanoes

  1. Ground Deformation
  2. Seismic Activity
  3. Gases
  4. Sensory Observations
• Ground Deformation 


  any surface changes on a volcano (subsidence sinking, tilting, buiging)
• Tiltmeter


  identifies the change of land area
• Seismic Activity


  when magma rises up, it breaks the rocks along the way 
• seismograph


  measures small tremors
• Gases 


  monitor types and rates of emissions of different gases

  -have foul smell
• Sensory Observations

  1. Visual
  2. Auditory
  3. Olfactory
  4. Tactile
• visual


  -vision

  -potential hazards that we can see
• Auditory

  • sense of hearing
  • ex: explosions, shaking, sounds of animals.
• Olfactory 


  hazardous smell
• tactile


  touch/feel

  -ex: temperature, heat, skin irritations.
• Lava flow


  is a highly elongated mass of molten rock materials cascading downslope from an erupting vent. The lava flow being extruded has low silica water content

  -gives time to escape
• 2 magma components 1. silica- higher silica, the higher viscosity

  2. water- more water, more movement