DRRR

• Volcano


  A vent, hill, or mountain from which molten or hot rocks with gaseous materials are or have been ejected

  
• Volcanic Eruption


  A process wherein molten rock materials are emitted or ejected in the form of flowing masses of lava or fragmental particles called pyroclastic with gas from a crater, vent, or fissure

  
• Volcanic Hazards


  • Pyroclastic Flow
  • Lava Flow
  • Ashfall
  • Lahar
  • Volcanic Gases
  • Debris Avalanche
  • Tsunami
  • Secondary Explosion
  • Ground Fissuring
  • Ballistic projectile

  
• Pyroclastic Flow


  • Fast turbulent mass of fragmented volcanic materials (ash and rocks) mixed with hot gases that flows downslope at very high speed (>60 kph)
  • The high temperature of a pyroclastic flow can burn everything along its path. Deposits of pyroclastic flows can bury areas within river valleys and plains

  
• Lava Flow


  • Stream-like flow of incandescent, molten rock material erupted from a volcano
  • Areas buried by lava flows will not be usable for a long time, because lava solidifies into massive rock

  
• Ashfall or Tephra Fall


  • Shower of fine-to-coarse-grained volcanic material and other airborne products if a volcanic eruption. Ashfall distributed or dispersal is dependent on prevailing wind direction
  • The fine particles, when inhaled, can cause respiratory problems. Thick heavy ash accumulations can cause roofs to collapse. Ashfall is particularly hazardous to aircrafts because it can cause jet engine failures

  
• Volcanic Gases


  • Gases released to the atmosphere in the form of water vapor, hydrogen sulfide, sulfur dioxide, CO, HCl, and HF
  • There are toxic gases emitted by volcanoes that can be harmful to health

  
• Debris Avalanche or Volcanic Landslide


  • A massive collapse of a huge portion of a volcano usually triggered by an earthquake or volcanic eruption

  
• Lahar


  • Rapidly flowing thick mixture of volcanic materials and water, usually generated along river channels by extreme rainfall
  • Lahar deposits can bury large areas under volcanic debris several meters thick

  
• Secondary Explosion


  • Non-eruption explosive events generated when ground water comes in contact with still hot pyroclastic flow deposits the stage of a volcano and converted to steam

  
• Ground Fissuring


  • Movement/ adjustment along faults, accompanied by earthquake
• Tsunami or Seiche


  • Waves or wave trains that are generated by the sudden displacement of water during volcanic eruptions. These could also be generated during undersea eruptions or by debris avalanches
• Ballistic projectile


  • Rock fragments that are ejected from a volcano's mouth and are comparable to cannonballs
  • The projectile can reach up to 5 km or 3 miles
• Natural Signs of an Impending Volcanic Eruption

  • Volcanic quakes
  • Steaming activity
  • Crater glow
  • Ground deformation
  • Localized landslides
  • Drying up of vegetation
  • Increase in temperature
  • Chemical content
  • Drying up of springs/wells
  • Thermal areas

  
• Volcanic quakes


  • Increase in the frequency of volcanic quakes with rumbling sounds and the occurrence of volcanic tremors

  
• Steaming activity


  • Increased steaming activity; change in color of steam from white to gray due to entrained ash
• Crater glow


  • A crater glows due to the presence of magma at or near the crater
  • A crater glow can be observed when the magma finally reaches the surface and is thus referred to as lava
• Ground deformation


  • Ground swells (or inflation), ground tilt, and ground fissuring due to magma intrusion
• Localized landslides


  • Rock falls and landslides from the summit area that are not attributed to heavy rains
• Drying up of vegetation

  • Noticeable increase in drying up of vegetation around the volcano's upper slopes
• Increase in temperature


  • Increase temperature of hot springs, wells (e.g. Bulusan and Canlaon) and crater lake (e.g. Taal) near the volcano
• Chemical content


  • Noticeable variation in the chemical content of springs, crater lakes within the vicinity of the volcano
  • Presence of certain compounds signals the presence of magma such as magmatic carbon dioxide, or high helium isotopes
• Drying up of springs/wells

  • Drying up of springs/ wells around the volcano
  • Rising magma generates quakes and tremors which may cause ground deformation (cracks or fissures) in the surface. This may cause the water to recede and seep though these cracks
  • As the magma rise, the temperature of the surface of the volcano also increase and if high enough, may cause the drying up of the springs and wells
• Thermal areas


  • Development of new thermal areas and/or reactivation of old ones; appearance of solfataras (craters with sulfur gas)