VOLCANO

Unit Overview

  • Unit 3, Module 1: Earth and Space

  • Prepared by: Darwin P. Velasco

Notable Volcanoes in the Philippines

Mount Apo

  • Location: Kidapawan, North Cotabato

Mount Mayon

Mount Tiwi

  • Location: Albay

Understanding Volcanoes

Definition

  • A volcano is an opening in the Earth's surface where molten rock, gas, smoke, and ashes are ejected.

Classification of Volcanoes

Active Volcanoes

  • Criteria: Erupted within the last 600 years or have recent activity based on material analyses.

Inactive Volcanoes

  • Criteria: No eruption in the last 10,000 years; physical forms altered by weathering and erosion, leading to gullies.

Types Based on Cone Shape

  1. Shield Volcanoes

    • Characterized by broad, gentle slopes; built from low-viscosity lava flows.

  2. Cinder Cone Volcanoes

    • Formed from volcanic cinders and have steep, conical shapes.

  3. Composite Cones (Strato-volcanoes)

    • Built from alternating layers of lava flows, ash, and other volcanic debris.

Characteristics of Different Volcano Types

Shield Volcano

  • Primarily built from layers of lava flows that are thin and spread over large areas.

Cinder Cone Volcano

  • Made from pyroclastic fragments that solidify as they fall.

Composite Volcano

  • Features both lava flows and cinders, creating a steep, symmetric structure.

Parts of Volcanoes

  • Magma: Molten rock stored beneath the Earth's surface.

  • Lava: Molten rock that has erupted onto the Earth's surface.

  • Crater: The bowl-shaped feature at the top of the volcano where eruptions occur.

  • Caldera: A large depression formed after a volcano erupts and collapses.

  • Summit: The highest point of the volcano.

  • Ash: Fine particles ejected during explosive eruptions.

Viscosity of Magma

Definition

  • Viscosity: The measure of a material's resistance to flow; related to thickness and stickiness.

Factors Affecting Viscosity

  1. Temperature: Higher temperatures lower viscosity.

  2. Composition: Silica content influences thickness; higher silica = higher viscosity.

  3. Gas content: Gassy magma can flow more easily; loss of gases increases viscosity.

Flow Characteristics

  • Low silica content lava can travel farther and forms thin sheets.

  • High silica content lava is very viscous; it piles up and can create plugs and domes.

Types of Volcanic Eruptions

  1. Phreatic (Hydrothermal): Steam-driven explosions due to heated groundwater.

  2. Phreatomagmatic: Explosive interaction of water and magma.

  3. Strombolian: Moderate explosions; characterized by solid bombs and lava bursts.

  4. Vulcanian: Short, violent eruptions; ejections of volcanic ash and rock.

  5. Plinian: Explosive, sustained, and powerful eruptions characterized by large ash clouds.

Geothermal Energy

Definition

  • Energy derived from the heat within the Earth's interior.

Generation Methods

  1. Geothermal Power Plants: Convert heat into electricity.

  2. Geothermal Heat Pumps: Utilize ground heat for heating and cooling purposes.

Short Quiz Questions

  1. What type of volcanic eruption is considered the most violent?

    • Answer: Plinian Eruption

  2. What eruption occurs when magma heats surface water?

    • Answer: Phreatic Eruption

  3. What do we call volcanoes that have not erupted in the past 10,000 years?

    • Answer: Extinct

  4. What do we call volcanoes that erupted within the last 600 years?

    • Answer: Active

  5. What does it mean for a volcano to be active but not erupting?

    • Answer: Dormant

Volcano Diagram Activity

  • Draw and label the parts of a volcano (e.g. ash, steam, gas, crater, lava, secondary cones, magma chamber).