Overview
This lecture covers plate tectonics and the relationship between active volcanoes, earthquake epicenters, and mountain ranges, especially around the Pacific Ring of Fire.
Healthy Screen Habits
- Sit properly with your back touching the chair's backrest for support.
- Change your sitting position regularly during long screen time.
- Use dim lighting in the room; avoid strong or no lighting to protect your eyes.
- Stretch or walk during breaks to prevent stiffness.
- Avoid watching TV in bed to prevent neck and back pain.
Key Concepts in Plate Tectonics
- Plate tectonics explains the features and movements of Earth’s surface, including past and present geological activity.
- The lithosphere is the 100 km thick layer of solid rock, including the crust.
- The asthenosphere, just below the lithosphere, is solid but softer and convects due to heat.
Distribution of Earthquakes, Volcanoes, and Mountains
- Earthquake epicenters, active volcanoes, and mountain ranges are concentrated in specific, often overlapping zones, not randomly distributed.
- These zones are especially evident around the borders of tectonic plates.
Major Global Geological Features
- Seven large tectonic plates: African, Antarctic, Eurasian, North American, South American, Indo-Australian, and Pacific plates.
- The Himalayas contain the world’s highest peaks, including Mount Everest.
- Cordillera Central and Sierra Madre are major mountain ranges in the Philippines.
The Pacific Ring of Fire
- The Pacific Ring of Fire, or Circum-Pacific Belt, is a region with many active volcanoes and frequent earthquakes.
- About 90% of the world's earthquakes occur in this region.
- The Philippines is part of the Ring of Fire and is prone to earthquakes and volcanic eruptions.
Notable Volcanoes and Events
- Mount Pinatubo (Philippines) erupted violently in 1991.
- Mount Fuji (Japan) and Mount St. Helens (USA) are other major active volcanoes on the Ring of Fire.
Pop Quiz Highlights
- The Pacific Ocean is surrounded by the Ring of Fire.
- Mount Pinatubo is a famous Philippine volcano due to its 1991 eruption.
- Sierra Madre is the longest mountain range in the Philippines.
- Australia has the least volcanic/earthquake activity among the choices.
- Earthquake epicenters, volcanoes, and moving plates in the Ring of Fire are situated in the same locations.
Key Terms & Definitions
- Epicenter — Point on Earth's surface directly above the earthquake’s origin.
- Mountain — Large landmass higher than hills, projecting above surroundings.
- Seismograph — Instrument that detects and records earthquake vibrations.
- Earthquake — Shaking of the ground from volcanic or tectonic activity.
- Volcano — Opening in Earth’s crust where molten rock, ash, and gases erupt.
- Lithosphere — Rigid outer layer of Earth, ~100 km thick, including the crust.
- Asthenosphere — Softer, partially molten layer beneath the lithosphere that enables plate movement.
- Ring of Fire — Zone of frequent earthquakes and volcanoes surrounding the Pacific Ocean.
Action Items / Next Steps
- Review your self-learning module and observe the given maps for plates, earthquakes, and volcanoes.
- Complete the “Re-circle the Ring” enrichment activity as described.
- Prepare for the next lesson on areas in the Philippines prone to geophysical hazards.