Overview
This lesson explains how the distribution of active volcanoes, earthquake epicenters, and major mountain ranges relates to plate tectonics, using the Philippines and the Pacific Ring of Fire as examples.
Structure of the Earth
- Earth is composed of four layers: crust, mantle, outer core, and inner core.
- There are two main types of crust: continental (thick, forms continents) and oceanic (thin, forms ocean floors).
The Lithosphere and Tectonic Plates
- The lithosphere is the rigid outer part of the Earth, including the crust and upper mantle.
- The lithosphere is broken into tectonic plates that move slowly due to mantle heat currents.
- Tectonic plates interact by moving apart, colliding, or sliding past one another.
Plate Tectonics and Geologic Features
- Plate collisions can create mountain ranges.
- Subduction (one plate going under another) leads to volcano formation.
- Movement or collision of plates can cause earthquakes, both on land and under the sea.
- Underwater earthquakes may trigger tsunamis.
Distribution of Volcanoes, Earthquakes, and Mountain Ranges
- Active volcanoes, earthquake epicenters, and mountain ranges often occur in the same or nearby areas due to plate boundaries.
- These features are not randomly distributed but are concentrated near tectonic plate boundaries.
The Philippines and Plate Tectonics
- The Philippines is located on the Pacific Ring of Fire, an area with frequent earthquakes and volcanic activity.
- Key tectonic plates affecting the Philippines: Philippine Sea Plate (east), Eurasian Plate (northwest), Pacific Plate (further east), and Sunda Plate (southwest).
- Plate interactions in this region create a highly active geological environment.
Summary of Plate Tectonics Theory
- Plate tectonics theory states Earth's crust is divided into moving plates, causing earthquakes, mountains, and volcanoes.
- Continental plates are thicker but less dense, while oceanic plates are thinner but denser.
- Major geologic activities occur near plate boundaries, especially at edges of continents.
Key Terms & Definitions
- Crust — Earth's outermost solid layer.
- Continental Crust — Thick, old crust forming land masses.
- Oceanic Crust — Thin, young crust forming ocean floors.
- Lithosphere — Rigid outer layer of Earth, including crust and upper mantle.
- Tectonic Plates — Large, moving pieces of lithosphere.
- Subduction — Process where one plate moves under another, forming volcanoes.
- Epicenter — Point on the Earth's surface vertically above the focus of an earthquake.
- Ring of Fire — Area around the Pacific Ocean with many volcanoes and earthquakes.
Action Items / Next Steps
- Review and understand how plate boundaries cause geological features.
- Watch the next lesson on plate boundaries.