VOLCANIC HAZARDS

• • Indonesian origin for "Lava or lava flow"
  • wet cement-like mixture of volcanic material and water
  • acquires older volcanic materials along rivers and other water channels

  Lahar
• Ashfall - consists of fragmented volcanic particles less than 2mm in diameter in size
• Tephra - fragmented volcanic particles in general
• Pyroclastic Flow - dense type of current that moves slower than surge
• Pyroclastic Surge - diluted type of current that has more mobility
• Pyroclastic Density Currents (PDC) - materials released from the mouth of the volcano after its explosion
• Ballistic Projectiles - may be likened to a cannonball usually landing 2-5 km away from the event
• Bombs - derived from fresh magma; attain smoothness and peculiar shapes before they fall
• Blocks - chips of the walls of the volcanic vent; rough with sharp edges
• Volcanic Gases - variety of gases released before and even after eruption
• Water vapor - colorless, odorless, and harmless; most abundant gas
• Carbon dioxide - colorless and odorless gas; may cause unconsciousness exceeding 15% concentration
• Sulfur Dioxide - colorless with pungent odor; irritant; may create smog
• Hydrogen Sulfide - colorless, flammable gas with strong offensive odor
• Hydrogen Halides - toxic acids that quickly dissolve in the atmosphere becoming components of acid rain; poisonous
• Lava flows - rivers of incandescent molten rocks flowing down a slope from an eruption vent
• Low silica magma - low viscosity lava flow; movement at high speeds
• High silica magma - high viscosity lava flow; movement at low speeds
• ● serves as a guide about danger zones and safe zones within

  the vicinity of the volcano

  ● basis of the country’s risk of volcanic eruption is based on the

  activity of volcanoes

  ● designated permanent danger zone and extended danger

  zone

  Hazard Maps