Plate tectonics - Seismic Tomography, Earth's Crust, Subduction

plate tectonics

Table of Contents

Introduction & Top Questions
Principles of plate tectonics
- Earth’s layers
- Plate boundaries
  - Divergent margins
    - Continental rifting
    - Seafloor spreading
  - Convergent margins
    - Subduction zones
    - Island arcs
    - Back-arc basins
    - Mountain building
      Mountains by subduction
      Mountains by terrane accretion
      Mountains by continental collision
  - Transform faults
- Hotspots
- Plate motion
  - Euler’s contributions
  - Past plate movements
Development of tectonic theory
- Precursors
- Alfred Wegener and the concept of continental drift
  - Isostasy
  - Driving forces
  - Evidence supporting the hypothesis
  - Disbelief and opposition
- Renewed interest in continental drift
  - Paleomagnetism, polar wandering, and continental drift
  - Gestation and birth of plate-tectonic theory
    - Discovery of ocean basin features
    - Hess’s seafloor-spreading model
    - The Vine-Matthews hypothesis
      Magnetic anomalies
      Reversal of Earth’s magnetic field
- Toward a unifying theory
  - Determination of plate thickness
  - Plate-driving mechanisms and the role of the mantle
    - Mantle convection
    - Seismic tomography
- Dissenting opinions and unanswered questions
  - Dissenters
  - Unanswered questions
Plate tectonics and the geologic past
- Wilson cycle
- Supercontinent cycle
- Continental reconstructions
Interactions of tectonics with other systems
- Oceans
  - Sea level
  - Composition of ocean water
- Life
  - Evolution
  - Extinction
- Climate

References & Edit History Related Topics

Images & Videos

What is the theory of continental drift?

Discern between body and surface waves, primary and secondary waves, and Love and Rayleigh waves

Examine how the theory of plate tectonics explains volcanic activity, earthquakes, and mountains

rift valley in Thingvellir National Park

For Students

plate tectonics summary

Read Next

Volcanic eruption of a volcano near Antigua, Guatemala

What Causes a Volcano to Erupt?

Paleogeography and paleoceanography of Early Triassic time. The present-day coastlines and tectonic boundaries of the configured continents are shown at the lower right. Continents, continental drift, plate tectonics, Pangea, Laurussia, Gondwana.

Spotting a Supercontinent: How Pangea Was Discovered

What’s the Difference Between Veins and Arteries?

earthquake. Heavily damaged school in the town of Yingxiu after a major earthquake struck China's Sichuan Province on May 12, 2008.

The 6 Deadliest Earthquakes Since 1950

Small canyon underwater carved by the swell into the fore reef with sunlight through water surface, Huahine island, Pacific ocean, French Polynesia.

A Tale of Two Submerged Continents

Discover

Queen Elizabeth II addresses at opening of Parliament. (Date unknown on photo, but may be 1958, the first time the opening of Parliament was filmed.)

All 119 References in “We Didn’t Start the Fire,” Explained

The Sun Was Eaten: 6 Ways Cultures Have Explained Eclipses

Mona Lisa, oil on wood panel by Leonardo da Vinci, c. 1503-06; in the Louvre, Paris, France. 77 x 53 cm.

Why Is the Mona Lisa So Famous?

Adolf Hitler (Nazi, nazism, German leader).

9 Things You Might Not Know About Adolf Hitler

9 of the World’s Deadliest Spiders

Albert Einstein in Washington, D.C. c. 1921-1923. Physicist

The Solar Eclipse That Made Albert Einstein a Science Celebrity

How Is Coffee Decaffeinated?

A powerful technique, seismic tomography, provides insight into the understanding of plate-driving mechanisms. This technique is similar in principle to that of the CT (computed tomography) scan and creates three-dimensional images of Earth’s interior by combining information from many earthquakes. Seismic waves generated at the site, or focus, of an earthquake spread out in all directions, similar to light rays from a light source. As earthquakes occur in many parts of Earth’s crust, information from many sources can be synthesized, mimicking the rotating X-ray beam of a CT scan. Because their speed depends on the density, temperature, pressure, rigidity, and ...(100 of 14904 words)

Access the full article

Help support true facts by becoming a member.