Hazards produced by volcanic activity

• Lava flows


  It depends on the type of lava. Basic (basaltic) lava is free-flowing and can run for considerable distances. Acidic lava such as rhyolite are thick and pasty so do not flow easily. Everything in the path of lava will be either burned, bulldozed or buried. Although lava destroys crops, infrastructure, they rarely cause any deaths or injuries.
• Pyroclastic flows


  These are a combination of very hot gases (500 degrees celisus +), ash and rock fragments travelling at high speed. They follow the contours of the ground and destroy everything in their path. The inhalation of such hot and poisonous gas causes almost instant death.
• Tephra


  Any material ejected from a volcano into the air. It ranges in size from very fine ash to large volcanic bombs. It is potentially very hazardous, burying farmland in layers of ash and destroying crops. Transport can be disrupted from both ground and air. Buildings can collapse due to the weight.
• Gases


  Eruptions emit a wide range of toxic gases, including CO, CO2 and SO2. These gases can pose a deadly (and silent) threat to human populations. When SO2 (sulfur dioxide) and water mix, acid rain is produced which is harmful for crops, pollute surface water and soils.
• Lahars

  Type of mud flow with the consistency of wet concrete. Rock fragments as well as ash and soil are mixed together. Lahars can travel at speeds up to about 50 km/h. Everything in their path is either buried or destroyed.
• Floods


  Volcanic eruptions beneath an ice field or glacier cause rapid melting. Large amounts of water accumulates until an exit is found.
• Tsunami


  it is a massive displacement of ocean water and can travel of speeds up to 600 km/h. in deep water they have a height that is usually less than 1 meter and a long wavelength of up to 200km. At the shore, tsunami waves increase rapidly in height and when they break, vast amounts of energy is transferred.