science - volcano

• The Philippines is home to several volcanoes due to its location in the Pacific Ring of Fire
• Volcano refers to a mountain or hill
• Crater or Vent is where lava, rock fragments, hot vapor, and gas are contained or have been erupted into the earth's surface
• Lava originated from molten materials called magma
• Magma is found beneath the surface of the Earth
• Volcanism includes any activity that involves the movement of magma toward or onto the surface
• Summit is the highest point or the apex of the volcano, with an opening called vent
• Slopes are the sides or flanks of a volcano radiating from the main or central vent
• Base is the lower outer part of the volcano
• Magma Chamber is a region beneath the vent of a volcano where molten rock or magma is deposited or stored before eruption
• Main Vent is the main opening or outlet on the surface of a volcano that emits lava, gases, ash, or other volcanic materials
• Conduit is an underground central tube-like or pipe-like structure that connects the magma chamber to the crater through which the magma travels
• Side Vent is a smaller outlet through which magma escapes
• Crater is the mouth of the volcano, a funnel-shaped or bowl-shaped hollow at the top of the vent from where magma, ash, and gas come out
• Lava is molten rock given off onto the surface of the Earth during a volcanic eruption
• Ash and Gas Cloud is a mixture of rock, minerals, glass particles, and gases expelled or pushed out of the volcano during a volcanic eruption
• Cinder Cone Volcano:

  • Simplest type of volcano
  • Built from particles and blobs of solidified lava ejected from a single vent
  • Most cinder cones have a steep slope and wide crater
  • Examples include Taal Volcano in Batangas and Mount Mayabobo in Quezon
• Composite Volcanoes or Stratovolcanoes:

  • Large, steep-sided, symmetrical cones formed from alternating layers of lava flows, volcanic ash, cinders, blocks, and pyroclastic materials
  • Formed from viscous lava that does not flow easily
  • Examples include Mount Mayon in Albay and Mount Arayat in Pampanga
• Shield Volcanoes:

  • Large, broad volcanoes built almost entirely of fluid lava flow
  • Easily identified by their tall and broad, flat, rounded shapes
  • Examples include Mauna Loa in Honolulu, Hawaii and Fernandina in Galapagos Island
• Types of Volcanoes Based on Activity:
• Active Volcanoes:

  • Volcanoes that have had at least one eruption during the past 10,000 years
  • Show regular activity like emission of gases, lava, and ash flows
• Inactive Volcanoes:

  • Volcanoes that have not erupted for the last 10,000 years and are not expected to erupt again in the future
  • Show no signs of volcanic activity for a long period due to cut-off magma supply and intensive weathering and erosion
• Potentially Active Volcanoes:

  • Volcanoes with no records of volcanic activity but are morphologically young-looking
• Phreatic or Hydrothermal:

  • Steam-driven eruption as hot rocks come in contact with water
  • Short-lived and characterized by ash columns
• Phreatomagmatic:

  • Violent eruption due to contact between water and magma, resulting in high-speed emission of pyroclastic materials
• Strombolian:

  • Periodic weak to violent eruption characterized by a fountain of lava
• Vulcanian:

  • Characterized by tall eruption columns with pyroclastic flow and ash fall tephra
• Plinian:

  • Excessively explosive eruption of gas and pyroclastic materials
• Signs of an Impending Volcanic Eruption:
• Increased steaming activity
• Crater Glow
• Landslide from summit areas
• Variation in the chemical content of springs and crater lakes
• Development of new thermal areas
• Increase in the temperature of wells and crater lakes near the volcano
• Ground swells
• Drying up of springs/wells around the volcano
• Drying of vegetation around upper slope
• Occurrence of volcanic tremors
• Magma is the molten rock underneath volcanoes, formed at destructive plate boundaries and rich in silicate