Volcano Hazards

• Volcanoes are opening on the earth's crust or surface.
• According to PHIVOLCS (Philippine Institute of Volcanology and Seismology), there are more than 20 active volcanoes in the past 600 years.
• Volcanoes can be classified into 3 classes: Active Volcanoes, Potentially Active Volcanoes, and Inactive Volcanoes.
• Active Volcanoes are volcanoes that are currently erupting, have erupted recently, and can erupt at any time.
• Potentially Active Volcanoes are volcanoes that have erupted once but were a long time ago and are now not showing any signs of erupting. It is also known as "dormant volcanoes" or "sleeping volcanoes".
• Inactive Volcanoes are volcanoes that show no signs of volcanic activity, and no records of eruption, but have all characteristics of a volcano. Also known as "extinct volcanoes"
• Sleeping volcanoes are volcanoes that have only erupted once or twice and stopped.
• Mayon Volcano located at Albay, has erupted 52 times. The first eruption was in 1616 and the last eruption was on June 12, 2023.
• Taal volcano located in Batangas, and has erupted 33 times based on the book, but has erupted 54 time based on research. First erupted during 1572, and its last eruption was on March 26, 2022.
• Kanlaon Volcano located in Negros Oriental, has erupted 30 times. First erupted in 1819, and its last eruption was in 2006.
• Bulusan Volcano located in Sorsogon, has erupted 15 times. First erupted in 1885, and its last eruption was on June 12, 2022.
• Smith Volcano located in Cagayan, has erupted 6 times. First erupted in 1831, and its last eruption was in 1924.
• Hibok-Hibok Volcano located in Camiguin, has erupted 4 times. First eruption was not recorded, and its last eruption was in 1953.
• Pinatubo Volcano located in Pampanga, has erupted 3 times. The first eruption was not recorded, and its last eruption was in June 15, 1991. Produced so much Lahar because it came together with Typhoon Yunya.
• Musuan Volcano located in Bukidnon, has erupted 2 times. The first eruption was not recorded, and its last eruption was in 1867.
• Potential Volcano-related Hazards include Lahar, Ash Fall, Pyroclastic Flow, Ballistic Projectile, Volcanic Gas, and Lava Flow.
• Lahar: a destructive and violent mudflow on the slopes of a volcano. Indonesian term for a mixture of water, pyroclastic materials, and rock fragments flowing down a volcano or river valley. Can be classified into 2: Hot lahar or Primary lahar which comes directly from volcanoes, and Cold lahar or secondary lahar which are primary lahar mixed with bodies of water.
• Ash Fall: Composed of bits and pieces of pulverized rocks, minerals, and volcanic glass generated from the volcanic eruption. Powderlike and airborne.
• Pyroclastic Flow: Fast-moving fluidized mass of rock fragments and gasses. came from the words Pyro meaning fire and Klastos meaning broken pieces. Can reach 60kph. Hot temperature smoke or gas that contains rocks. Can cause burns due to the hot gases.
• Ballistic Projectile: Rock Fragments ejected by the volcano. Has 2 types, Blocks which are rock fragments only and are solid when ejected, and Bombs which are partially melted rocks that may still be liquid or molten.
• Volcanic Gas: Consists of sulfur dioxide and hydrogen sulfide, which are colorless, poisonous, and hazardous. Foul smelling and can be used to detect an upcoming eruption.
• Lava Flow: Molten rocks that pour down from the volcano or its slopes. It is called lava when magma is out of the volcano, and magma if it is still inside the volcano.
• Signs of an Impending Volcanic Eruption:

  • The occurrence of tremors increases in the frequency of small earthquakes.
  • Deformation of the ground is manifested by changes in the ground elevation.
  • Increase in the number of volcanic gases.
  • Growth of volcanic crater.
  • Increase in steam emission coming from volcanic openings.
  • Thermal changes within the surroundings of the volcano.
  • Change in the color of the nearby vegetation and lakes.
  • Landslides and rock Fall not due to heavy rains.
  • Drying up of Springs and freshwaters.