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)

2. 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)

3. Shield Volcanoes:

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

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

   • Examples:

     • Mauna Loa (USA)

4. 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.