Volcano

3rd Quarter Earth and Space

VOLCANO Definition, Parts and Types

Location of the Philippines

  • The Philippines is situated along the Ring of Fire, making it geologically active.

  • Approximately 300 named and unnamed volcanoes exist in the archipelago.

  • There are currently 22 classified active volcanoes.

  • Six of the most active volcanoes:

    • Pinatubo

    • Taal

    • Mayon

    • Bulusan

    • Kanlaon

    • Hibok-Hibok

Importance of Volcanic Knowledge

  • According to the Philippine Institute of Volcanology and Seismology (PHIVOLCS):

    • The country is an ideal site for volcanic activity.

    • It is imperative to understand this phenomenon to mitigate risks and adverse effects.

What is a Volcano?

  • A volcano is defined as a vent, hill, or mountain where molten or hot rocks with gas materials are ejected.

  • This term also refers to craters, hills, or mountains formed from the accumulation of ejected materials or the removal of pre-existing materials.

Parts of a Volcano

Key Components

  • Volcanic Bombs: Larger debris out thrown during an eruption.

  • Ash, Steam, & Gas: Cloud expelled from the volcano.

  • Crater: Circular depression at the volcano's summit.

  • Main Vent: Tube connection between magma chamber and surface.

  • Lava: Molten rock after reaching the surface.

  • Secondary Cone: Cone that forms around secondary vents.

  • Secondary Vent: Entry point of magma to surface without going through main vent.

  • Magma: Molten rock beneath the earth's crust.

  • Magma Chamber: Underground storage for magma.

Types of Volcanoes

Classification by Activity

  • Active Volcano: Recently erupted and continues to do so.

  • Dormant (Potentially Active) Volcano: Historically silent for over 2,000 years but may erupt again.

  • Inactive (Extinct) Volcano: No eruptions in over 10,000 years, not expected to erupt.

Classification by Structure

  • Shield Volcano: Broad base, gentle slopes. Example: Mayon

  • Cinder Cone Volcano: Smallest type with steep slopes, formed by ejected fragments. Example: Mount Bulusan

  • Composite Volcano (Stratovolcano): Large structure with steep sides formed from alternating layers of lava and ash. Example: Mount Mayon

Eruptive Styles of Volcanoes

  • Effusive Eruption: Lava flows steadily from vent, characterized by less explosive activity.

  • Explosive Eruption: Fragmented lava violently expelled from vents, resulting in ash clouds and pyroclastic flow.

Volcanic Hazards and Effects

Negative Effects

  • Loss of lives and destruction of properties.

  • Pyroclastic flows can devastate areas in their path.

Positive Effects

  • Volcanic eruptions can improve soil fertility by adding essential nutrients.

  • Eruptions can create scenic landscapes and other tourism opportunities.

Monitoring Volcanic Eruptions

Methods Used

  • Seismic Activity: Earthquake monitoring near volcanoes indicates magma movement.

  • Ground Deformation: Instruments monitor shape changes of volcanoes.

  • Gas Emissions: Analyzing gases emitted can signal rising magma.

  • Temperature Changes: Thermal imaging detects surface temperature changes indicative of magma.

Benefits of Volcanoes to Earth

  • Geological Processes: Contributes to new landforms like mountains and islands.

  • Nutrient Cycling: Eruptions enrich soils with essential nutrients, supporting plant growth and ecosystems.