Overview
This lecture covers essential health tips for screen time and provides an introduction to plate tectonics, focusing on the distribution of earthquakes, volcanoes, and mountain ranges, with activities and a short quiz.
Healthy Screen Time Tips
- Sit properly with your back touching the chair's backrest for support.
- Change your position regularly if watching for long periods.
- Keep dim lighting on in the room to prevent eye damage.
- Use commercial breaks to stretch or walk around.
- Avoid watching TV in bed to prevent neck and back pain.
Introduction to Plate Tectonics
- Plate tectonics explains the features and movements of Earth's surface.
- The lithosphere (crust and uppermost solid mantle, ~100 km thick) is broken into plates.
- The asthenosphere (beneath lithosphere) is softer and allows convection, driving plate movement.
Key Plate Tectonics Terms & Their Distribution
- Earthquakes, volcanoes, and mountain ranges are not randomly distributed; they are often found together, especially at plate boundaries.
- There are seven major plates: African, Antarctic, Eurasian, North American, South American, Indo-Australian, and Pacific.
- The Philippines is located in the Pacific Ring of Fire, an area with frequent earthquakes and volcanic eruptions.
Maps & Observations
- Earthquake epicenters are concentrated in narrow zones, often at plate edges.
- Most active volcanoes are found along continental edges, especially the Pacific Rim.
- Major mountain ranges (e.g., Himalayas, Cordillera Central, Sierra Madre) align with tectonic boundaries.
Important Examples
- Mount Pinatubo in the Philippines erupted violently in 1991.
- Other notable volcanoes: Mount Fuji (Japan) and Mount St. Helens (USA).
- Sierra Madre is the Philippines’ longest mountain range, providing a barrier against typhoons.
Summary of Plate Movements & Effects
- Plate movements cause earthquakes, volcanic activity, and mountain building.
- Earthquakes can occur on land or under the sea (can cause tsunamis).
- 90% of the world's earthquakes occur in the Pacific Ring of Fire.
Key Terms & Definitions
- Epicenter — Point on Earth's surface directly above an earthquake's focus.
- Mountain — Large landform rising above surrounding land, higher than a hill.
- Seismograph — Instrument that detects and records earthquake vibrations.
- Earthquake — Shaking of Earth's surface caused by tectonic or volcanic activity.
- Volcano — An opening in Earth's crust through which lava, ash, and gases erupt.
- Lithosphere — Rigid outer layer of the Earth, including the crust and upper mantle.
- Asthenosphere — Softer, ductile layer beneath the lithosphere allowing plate movement.
- Ring of Fire — Zone around the Pacific Ocean with high volcanic and earthquake activity.
Action Items / Next Steps
- Review maps in your self-learning module to observe plate movement and distributions.
- Complete any enrichment activities on the Ring of Fire in your module.
- Prepare for the next lesson on areas in the Philippines prone to geophysical hazards.