Plate Tectonics Overview

Study Notes

Plate Tectonics

Plate tectonics is the theory that Earth's lithosphere (the rigid outer shell) is divided into several large and small plates that move relative to each other.
These plates are constantly moving, albeit very slowly, driven by convection currents in the Earth's mantle.
The movement and interaction of these plates cause various geological phenomena, including earthquakes, volcanoes, mountain ranges, and the formation of new ocean floor.
The plates ride on semi-molten rock in the upper mantle.
The plates float on the asthenosphere, a weaker, partially molten layer beneath the lithosphere.

Types Of Plate Boundaries

Divergent Boundaries: Plates move apart, creating new crust.
- Magma rises from the mantle, creating new oceanic crust.
- Often found in the middle of ocean ridges.
- Characterized by volcanic activity and shallow earthquakes.
Convergent Boundaries: Plates move towards each other.
- Oceanic-Continental Convergence: Oceanic plate subducts beneath the continental plate, creating a trench and volcanic mountain range.
- Oceanic-Oceanic Convergence: Denser plate subducts, creating a trench and volcanic island arc.
- Continental-Continental Convergence: Two continental plates collide, creating a mountain range.
- Characterized by intense earthquakes, often deep, and volcanic activity at subduction zones.
Transform Boundaries: Plates slide past each other horizontally.
- Characterized by frequent shallow earthquakes.
- Common along mid-ocean ridges and around fault lines.

Earthquakes

Earthquakes are sudden releases of energy in the Earth's lithosphere that create seismic waves.
These waves radiate outward from the hypocenter (focus) causing ground shaking.
The epicenter is the point on the surface above the focus.
Fault lines are areas where the Earth's crust has fractured, and along these lines earthquakes occur.
Magnitude of the quake represents the amount of energy released, measured using the Richter scale or the moment magnitude scale.
Intensity describes the effects of the earthquake at a particular location.
Tectonic plate movements are the primary cause of most large earthquakes.

Volcanoes

Volcanoes are openings in the Earth's crust through which molten rock (magma), ash, and gases erupt.
Magma, when it reaches the surface, is called lava.
Volcanic eruptions can be effusive (slow, flowing lava) or explosive (sudden, violent eruptions of ash and gas).
Volcanoes are typically found at convergent plate boundaries, divergent plate boundaries, and hotspots.
Volcanic activity is closely linked to tectonic plate movements and the subduction of crustal plates.
Location of volcanoes gives insight into plate tectonic movement.
The materials erupted from volcanoes can cause significant damage to the environment and human infrastructure.

Tectonic Plate Movement

Plate movement is driven by convection currents in the Earth's mantle.
Heat from the Earth's core causes the mantle to become less dense and rise.
Cooler, denser mantle material sinks, creating a cycle of convection.
This movement drags the overlying tectonic plates, causing them to move slowly over time.
The rate of plate movement is typically a few centimetres per year.
This movement is responsible for the creation and destruction of Earth's landforms and geological features.
Plate movement also creates geological hotspots and mantle plumes, which contribute to the formation of volcanoes.
Evidence for plate movement includes the fit of continents, the distribution of fossils, and the paleomagnetic record.

Description

Explore the fundamental concepts of plate tectonics, including the structure of the Earth's lithosphere and the dynamics of plate movement. This quiz covers different types of plate boundaries, their characteristics, and the geological phenomena resulting from their interactions.