Overview
This lecture explains the global distribution of earthquake epicenters, active volcanoes, and major mountain belts, highlighting their relationship to plate tectonics.
Distribution of Earthquake Epicenters
- Earthquakes are vibrations caused by rocks breaking under stress.
- Earthquake epicenters are mostly found along the boundaries of lithospheric plates.
- Countries near plate boundaries, like the Philippines, experience frequent and strong earthquakes.
- Some earthquakes, called intraplate earthquakes, occur within a plate due to stress in rocks.
- Predicting the exact time and location of earthquakes is currently not possible.
Distribution of Active Volcanoes
- A volcano is an opening in the Earth's crust where magma, ash, and gas escape.
- Active volcanoes are primarily found along plate boundaries.
- Most volcanoes are located on the Pacific Ring of Fire, marking the edges of several tectonic plates.
- Countries far from plate boundaries rarely experience volcanic eruptions.
Distribution of Major Mountain Belts
- Mountain ranges are chains of mountains sharing geological origins, typically at convergent plate boundaries.
- The major orogenic (mountain building) belts are the Circum-Pacific and Alpine-Himalayan belts.
- The Himalayas formed from the collision of the Indian and Eurasian plates and continue to grow today.
- The Andes mountains formed from the subduction of the Nazca plate beneath the South American plate.
- The distribution of mountain belts closely aligns with earthquake epicenters and volcano locations.
Key Terms & Definitions
- Plate Tectonics — Theory explaining the movement of Earth's lithospheric plates.
- Lithospheric Plates — Rigid segments of Earth's outer shell.
- Earthquake Epicenter — Point on Earth's surface directly above where an earthquake originates.
- Volcano — Opening in Earth's crust releasing magma, ash, and gases.
- Orogeny — The process of mountain building due to tectonic movements.
- Ring of Fire — Area in the Pacific where many earthquakes and volcanoes occur.
Action Items / Next Steps
- Complete the activity: Compare maps of lithospheric plates, earthquake epicenters, volcanoes, and mountain belts to observe their relationships.
- Review specific examples like the Himalayas and Andes for understanding tectonic processes.