Overview
This lecture explains how the distribution of volcanoes, earthquake epicenters, and major mountain ranges relates to the theory of plate tectonics, with a focus on the Philippines.
Layers of the Earth
- Earth has four layers: crust, mantle, outer core, and inner core.
- The crust consists of two types: continental crust (thicker, older, forms continents) and oceanic crust (thinner, denser, forms ocean floors).
Lithosphere and Plate Tectonics
- The lithosphere is the outermost layer, including the crust and upper mantle.
- The lithosphere is broken into tectonic plates that slowly move.
- Movement of plates is driven by heat currents in the mantle.
Plate Movements and Geological Features
- Colliding plates can form mountain ranges.
- When one plate subducts (dives) under another, volcanoes can form.
- Plates sliding past or colliding cause earthquakes.
- Plate tectonics explains the distribution of mountains, earthquakes, and volcanoes on Earth.
Distribution of Geological Activity
- Active volcanoes, earthquake epicenters, and mountain ranges are usually close together or in the same locations.
- On land, earthquakes are caused by tectonic movement or volcanic eruptions; underwater earthquakes can trigger tsunamis.
- These features are common near plate boundaries.
The Ring of Fire and the Philippines
- The Philippines is part of the Pacific Ring of Fire, a zone with frequent earthquakes and volcanoes.
- The region is geologically active due to intersecting tectonic plates: Philippine Sea Plate, Eurasian Plate, Pacific Plate, and Sunda Plate.
- These plates' interactions make the Philippines prone to earthquakes and volcanic eruptions.
Key Terms & Definitions
- Continental Crust — Thick, less dense part of Earth's crust forming continents.
- Oceanic Crust — Thin, dense crust under oceans.
- Lithosphere — Rigid outer layer of Earth, made of crust and upper mantle.
- Tectonic Plates — Large, moving pieces of the lithosphere.
- Plate Tectonics — Theory that Earth's surface is divided into plates that move and interact.
- Subduction — Process where one plate dives beneath another, often forming volcanoes.
- Epicenter — Point on Earth's surface directly above an earthquake's focus.
- Ring of Fire — Area around the Pacific Ocean with high volcanic and earthquake activity.
Action Items / Next Steps
- Review plate boundaries for the next lesson.