Science 9 Quarter 2

• Volcano


  A vent or opening that expels molten rock or magma from the interior of Earth
• Shield Volcano


  • Mountain with broad, gently sloping sides and nearly circular base, formed when layers of basaltic lava accumulate during nonexplosive eruptions
• Hotspots are regions in Earth's mantle due to high-temperature mantle plumes that rise toward the surface, melting rock and forcing magma towards the crust. The magma then flows upward to Earth's surface as lava
• Fissure Volcano


  • Volcanic vent through which lava erupts without explosive activity, lava spreads to form huge pools which then cool and solidify
• Majority of volcanoes in the world form along the boundaries of Earth's tectonic plates, which are massive expanses of our planet's lithosphere that continually shift, bumping into one another
• Calderas are formed when the summit or the side of the volcano collapses into magma chambers, resulting in collapsed walls and cliffs above the surface of water
• Cinder Cone Volcano


  • Steep conical hill of volcanic debris with a bowl-shaped center, eruptions from a single opening expel rock fragments called scoria or cinders
• Type of Volcano according to appearance

  • Fissure Volcano
  • Cinder Cone Volcano
  • Composite Volcanoes
  • Shield Volcano
• Composite Volcanoes

  • Majestic volcano with tall symmetry, formed when layers of volcanic fragments alternate with lava, also known as strato volcano
• Formation of Volcanoes


  Occurs along the boundaries of Earth's tectonic plates where one plate often plunges deep down below the other in a subduction zone
• Shield Volcano


  A mountain with broad, gently sloping sides and a nearly circular base, formed when layers of basaltic lava accumulate during nonexplosive eruptions
• Types of volcanic fragments

  • Volcanic ash
  • Cinders
  • Lava
  • Scoria
  • Ash flow deposits
• Dormant Volcanoes may have the capacity to erupt later on, with long intervals between their last eruption and the latest one
• Lapillus

  Volcanic fragments with sizes ranging from 2mm to 64 mm, come in different shapes like teardrop, dumbbell, or spheroid, made up of molten or semi-molten lava ejected from a volcanic eruption
• Volcanic Ash

  Very fine-grained fragments of pulverized rocks, minerals, and volcanic glass, formed when dissolved gases in magma expand and escape violently into the atmosphere
• Formation of layers in stratovolcanoes

  Stratification
• Inactive Volcanoes are those that have not erupted in history but still have the potential to do so
• Lahar

  Also known as mud flow or debris flow, mixtures of volcanic debris and water, classified into primary or hot lahars from volcanic eruption and secondary or cold lahars due to heavy rainfall
• Volcanic Bombs

  Masses of molten rocks larger than 65 mm, formed when a volcano ejects viscous fragments of lava with a hard outer rock shell and liquid inside
• Stratovolcano

  Also known as strato volcano, formed by layers of volcanic fragments such as volcanic ash and cinders alternating with lava
• Active Volcanoes are presently erupting or have erupted in the last 10,000 years, expected to erupt sooner rather than later
• Pyroclastic materials

  • Volcanic ashes
  • Volcanic bombs
  • Volcanic blocks
  • Lapillus
  • Lahar
• Volcanic Blocks


  Solidified fragments greater than 64 mm in diameter, ejected from explosive volcanic eruptions, consisting of broken pieces of the volcano's edifice
• Composite Volcano, also known as stratovolcano, is tall and symmetrically shaped, formed by layers of volcanic fragments alternating with lava
• Volcanoes on Earth are not randomly distributed. Around 80% of volcanoes are located along convergent plate boundaries, 15% along divergent plate boundaries, and about 5% far from plate boundaries. Volcanoes far from plate boundaries form as a result of hotspots
• Calderas formed

  Calderas are formed when the summit or the side of the volcano collapses into the magma chamber, creating cliffs that stand several meters above the surface of water
• Cinder cone Volcano has a steep conical hill of volcanic debris and a bowl-shaped crater, created by eruptions from a single opening, with rock fragments called scoria or cinders being expelled
• How does volcano form?

  The majority of volcanoes in the world form along the boundaries of Earth’s tectonic plates, which continually shift and bump into one another. When tectonic plates collide, one often plunges deep below the other in a subduction zone
• Types of Volcanoes According to Activity

  • Active volcanoes
  • Dormant volcanoes
  • Inactive volcanoes
• Active volcanoes are presently erupting or have erupted in the last 10,000 years, expected to erupt sooner rather than later. Dormant volcanoes may erupt later on with long intervals between eruptions. Inactive volcanoes are not currently erupting
• Vulcan

  The God of Fire in Roman mythology
• Fissure Volcano erupts lava without explosive activity, forming cracks in the ground and expelling vast quantities of lava
• Types of Volcano According to Appearance

  • Fissure Volcano
  • Cinder cone Volcano
  • Composite Volcano
  • Shield Volcano
• Volcano

  A volcanic island in the Aeolian Islands of Italy, vents or openings that expel molten rock or magma from the interior of Earth
• Anatomy of Volcanoes

  • Flank
  • Summit
  • Magma reservoir
  • Conduit
  • Dikes
  • Vent
  • Crater
  • Base
  • Silt
  • Ash cloud
  • Parasitic Cone
• Shield Volcano is a mountain with broad, gently sloping sides and a nearly circular base, formed by basaltic lava accumulating during nonexplosive eruptions
• Hotspots are hot regions in Earth’s mantle due to high-temperature mantle plumes that rise toward the surface, melting rock and forcing it toward the crust as magma, which then flows upward to Earth’s surface as lava
• Inactive volcanoes

  • Those that have not erupted in history but still have the potential to do so
  • Those that have not erupted in the past 10,000 years
• Dormant Volcanoes in the Philippines

  • Apo, Cuernos de Negros, Gorra, Maripipi, Mariveles, Negron, Angeles City, Olongapo City
• Volcanic Ashes


  Very fine-grained fragment of pulverized rocks, minerals, and volcanic glass formed during volcanic eruptions