3rd quarter PPT week 1

Introduction

  • Good morning, Students! God is good.

Volcanoes: Science 9 – Earth and Space

  • Topic for Third Quarter.

Objectives

  • At the end of the discussion, students will be able to:

    • Describe the structure of a volcano.

    • Describe the different types of volcanoes based on structure and activity.

    • Give examples of the types of volcanoes found in the Philippines.

    • Describe the different types of volcanic eruptions.

    • Create advocacy materials or activities to raise awareness about signs of impending volcanic eruptions.

Definition of Volcano

  • A volcano is a rupture in the Earth's crust allowing hot lava, volcanic ash, and gases to escape from a magma chamber.

  • The process of forming volcanoes is called volcanism.

Structure of a Volcano

  • Key Structures:

    • Summit: The highest point of the volcano, has an opening called the vent.

    • Slopes: The flanks that radiate from the main vent.

    • Base: The lower outer part of the volcano.

  • Other Geologic Features:

    • Magma Chamber: A large pool of liquid rock beneath the surface; drives the volcanic eruption.

    • Main Vent: The main outlet on the surface for lava, gases, ash, etc.

    • Conduit: An underground pipe connecting the magma chamber to the crater.

    • Side Vent: Smaller outlets for magma escape.

    • Crater: The funnel-shaped hollow at the top of the vent.

Types of Volcanoes

Based on Structure

  1. Cinder Cone Volcanoes:

    • Simple structure, steep slopes, wide crater, most abundant type.

    • Form from violent eruptions throwing lava fragments into the air which cool and fall as cinders.

Examples of Cinder Cone Volcanoes in the Philippines

  • Taal Volcano (Batangas)

  • Smith Volcano (Babuyan Group of Islands)

  • Mount Mayabobo (Quezon Province)

  • Mount Musuan (Bukidnon)

  • Paricutin Volcano (Mexico)

  1. Composite Volcanoes (Stratovolcanoes):

    • Cone-shaped, consists of layers of lava, pumice, ash, and tephra.

    • Form tall peaks due to viscous lava.

    • Examples in the Philippines:

    • Mount Mayon (Albay)

    • Mount Arayat (Pampanga)

    • Mount Kanlaon (Negros)

    • Mount Apo (Davao Region)

  2. Shield Volcanoes:

    • Large, broad, gentle slopes, looks like a shield.

    • Formed mostly by fluid lava flows, relatively safe eruptions.

    • Examples:

      • Mauna Loa (USA)

  3. Volcanic Domes:

    • Form from slow extrusion of thick silicic lava.

    • Often small, may not have a crater.

Classification of Volcanoes by Activity

Types Based on Activity

  • Defined by the Philippine Institute of Volcanology and Seismology (PHIVOLCS).

  1. Active Volcanoes:

    • Erupted in the last 10,000 years; show signs of activity.

  2. Inactive Volcanoes:

    • Have not erupted in the last 10,000 years, with no expected future activity.

  3. Potentially Active Volcanoes:

    • No eruption records but have a young morphology.

  • Active Volcanoes in the Philippines:

    • Mount Banahaw

    • Mount Hibok-Hibok

    • Mount Kanlaon

    • Mount Apo

Signs of Impending Volcanic Eruption (According to PHIVOLCS)

  • Increased volcanic activity:

    • Increased steaming and tremors.

    • Crater glow.

    • Drying vegetation.

    • Landslides on upper slopes.

    • Variations in chemical content of springs.

    • Ground swelling and increased temperature.

Types of Volcanic Eruptions

  1. Phreatic:

    • Steam-driven eruptions; occurs when hot rocks contact water.

  2. Phreatomagmatic:

    • Violent eruptions due to contact between water and magma.

  3. Strombolian:

    • Characterized by weak to violent fountain lava eruptions.

  4. Vulcanian:

    • Tall eruptions reaching up to 20 km high with pyroclastic flow.

  5. Plinian:

    • Extremely explosive eruptions with gas and pyroclastics.

Reasons for Volcanic Eruptions

  1. Density-Difference in Magma:

    • Pressure causes lighter magma to rise through denser material.

  2. Pressure from Released Gases:

    • Gas saturation leads to explosive eruptions.

  3. Injection of New Magma:

    • New magma increases pressure, causing eruptions.

Effects of Volcanic Eruptions

Negative Effects:

  • Destruction of life and property; evacuations may occur.

  • Ash discharge can harm the ozone layer.

  • Formation of lahars (mudflows).

Deadliest Volcanic Eruptions:

  1. MT. TAMBORA, INDONESIA – 92,000 deaths

  2. MT. UNZEN, JAPAN – 12,000 to 15,000 deaths

  3. MT. VESUVIUS, ITALY – 10,000+ deaths

  4. MT. PELEE, WEST INDIES – 40,000 deaths

  5. MT. KRAKATOA, INDONESIA – 36,000 deaths

Positive Effects:

  • Geothermal energy generation.

  • Ash as a natural fertilizer.

  • Tourism generated by volcanic scenery.

  • Valuable minerals brought to the surface.

Volcano Alert Levels by PHIVOLCS

  1. Alert Level 0: Quiet or no alert.

  2. Alert Level 1: Low level of unrest; no imminent eruption.

  3. Alert Level 2: Increasing unrest; possible future eruption.

  4. Alert Level 3: Magmatic unrest; include seismic activity.

  5. Alert Level 4: Hazardous eruption imminent.

  6. Alert Level 5: Hazardous eruption in progress.

Safety Tips

  • Distance from active volcanoes is crucial.

  • Emergency kit essentials: goggles, masks, flashlight.

  • Know evacuation routes.

  • Prepare home by sealing windows and doors.

Conclusion

  • Understanding volcanoes and their structures is essential to mitigate risks and take advantage of their benefits.

  • Following research and preventive measures can help reduce danger to life.

Closing

  • Thank you, God Bless You.