Volcanic hazards

• The only effective mitigation against pyroclastic flow is evacuation.
• DIRECT VOLCANIC HAZARDS:

  Laterally-directed thrusts of hot gas and ash that can be generated from an exploding dome on the summit vent or inside the edifice. Lateral Blasts
• Lateral blasts occur when sudden mass failure of the volcanic flanks occur.
• Blasts travel at subsonic speeds on the onset.
• DIRECT VOLCANIC HAZARDS:

  Gases and aerosols released into the atmosphere, which include water vapor, hydrogen sulfide, sulfur dioxide, carbon monoxide, hydrogen chloride, hydrogen fluoride. Volcanic gas
• Volcanic gas may also be released from the erupted magma.
• Volcanic gas effects:

  irritating to eyes, skin and respiratory system. Sulfur dioxide
• Volcanic gas effects:

  very toxic in high concentrations. hydrogen sulfide
• volcanic gas effects:

  strong,toxic acids. Hydrogen hallides
• volcanic gas effects:

  deform and kill animals that grazed on vegetation covered with volcanic ash. fluorine compounds
• INDIRECT VOLCANIC HAZARDS:

  Rapidly flowing thick mixture of volcanic sediments and water, usually triggered by intense rainfall during typhoons and monsoons. Lahar, flooding
• INDIRECT VOLCANIC HAZARDS:

  Sea waves or wave trains that are generated by sudden displacement of water. Tsunami
• Tsunami could be generated by:

  violent explosions from underwater volcanoes
• Tsunami could be generated by:

  voluminous pyroclastic materials discharging into the sea
• Tsunami could be generated by:

  Volcanic landslides
• Delineated and identified area where no permanenthabitation is recommended due to the possible impact ofvarious hazards at any time. Permanent danger zone
• PDZ for Bulusan and Kanlaon. 4 km
• PDZ for Mayon. 6 km
• In the Philippines, we use a system of Volcano AlertSignals to define the current status of each volcano. Volcanic alert levels
• VOLCANO ALERT LEVELS:

  low level unrest, no eruption imminent, 6 km PDZ. alert level 1
• VOLCANO ALERT LEVELS:

  moderate unrest, could lead to eruption, 6-7 km PDZ. alert level 2
• VOLCANO ALERT LEVELS:

  relatively high unrest, eruption within weeks, extension of PDZ. alert level 3
• VOLCANO ALERT LEVELS:

  intense unrest, eruption in days, 8 km PDZ. alert level 4
• VOLCANO ALERT LEVELS:

  hazardous eruption ongoing. alert level 5