Understanding Volcanoes and Eruptions

Dec 15, 2024

Maesrang Techie YouTube Channel: Grade 9 Science - Volcanoes

Introduction

  • Welcome back to the channel! Congratulations on reaching quarter 3 of Grade 9 Science.
  • Focus for this quarter: Earth Science
  • Current Topic: Types of Volcanoes and Volcanic Eruptions

Key Terminology

  • Volcano: Natural opening on Earth's surface ejecting molten rocks, smoke, gases, and ashes.
    • Example: Mayon Volcano in Albay, Bicol, Philippines.
  • Crater: Funnel-shaped depression at a volcano's summit.
    • Example: Taal Volcano with 47 craters.
  • Caldera Collapse: Triggered by the emptying of the magma chamber post-eruption.
  • Magma: Hot fluid/semi-fluid material below Earth's crust.
  • Lava: Magma that reaches Earth's surface.

Types of Volcanoes (by Shape)

  1. Shield Volcano
    • Formed by non-viscous lava flows.
    • Broad, dome-shaped structure.
    • Example: Mauna Loa in Hawaii.
  2. Cinder Cone Volcano (Scoria Cone)
    • Built from ejected lava fragments.
    • Steep slopes, wide craters.
    • Example: Mount Percutin in Mexico.
  3. Composite Volcano (Stratovolcano)
    • Formed from alternating lava and pyroclastic deposits.
    • Example: Mayon Volcano.

Reasons for Different Types of Volcanoes

  • Magma formation varies with tectonic settings and plate boundaries.

Types of Volcanic Eruptions

  1. Phreatic Eruption
    • Steam-driven due to water-rock contact.
    • Example: Taal Volcano (January 12, 2020).
  2. Phreatomagmatic Eruption
    • Water-magma interaction causing violent ash eruptions.
  3. Strombolian Eruption
    • Characterized by fountain lava eruptions.
  4. Vulcanian Eruption
    • Tall eruptions with pyroclastic flow; reach up to 20 km high.
  5. Plinian Eruption
    • Excessively explosive gas and pyroclastic eruptions.
    • Example: Mount Pinatubo (1991).

Classification of Volcanoes by Activity

  • Active Volcano: Has a record of eruptions.
  • Inactive Volcano: No activity or record of eruptions.
    • Example: Mount Canlaon in Negros Occidental, Philippines.

Conclusion

  • Volcanoes play a vital role in sustaining life by keeping the Earth warm and wet.
  • More details will be covered in the next video.