Earth’s Tectonic Plates

 

Tectonic Plates

Plate tectonics is the generally accepted scientific theory that considers the Earth’s lithosphere to comprise a number of large tectonic plates which have been slowly moving since about 3.4 billion years ago. Tectonic plates are composed of the oceanic lithosphere and the thicker continental lithosphere, each topped by its own kind of crust. Along convergent boundaries, the process of subduction, or one plate moving under another, carries the edge of the lower one down into the mantle; the area of material lost is balanced by the formation of new (oceanic) crust along divergent margins by seafloor spreading. In this way, the total geoid surface area of the lithosphere remains constant. This prediction of plate tectonics is also referred to as the conveyor belt principle. Earlier theories, since disproven, proposed gradual shrinking (contraction) or gradual expansion of the globe.

Continental Drift

Continental drift describes one of the earliest ways geologists thought continents moved over time. Today, the theory of continental drift has been replaced by the science of plate tectonics. The theory of continental drift is most associated with the scientist Alfred Wegener.

Earthquakes

The earth's tectonic plates have moved and are still constantly moving. When two tectonic plates slide past each other, they cause tension between them which leads to the formation of an earthquake. 

Underwater Earthquakes

A submarine, undersea, or underwater earthquake is an earthquake that occurs underwater at the bottom of a body of water, especially an ocean. They are the leading cause of tsunamis.

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