Tectonic Plates, Earthquakes, and Volcanoes | PBS LearningMedia
What is the relationship between volcanoes, earthquakes, and plate-tectonics? Plate tectonics is the over-lying theory presently used by most Earth Scientists to . Earthquake belts and distribution. Earthquakes occur in well‐defined belts that correspond to active plate tectonic zones. The circum‐Pacific be. The skin is divided into about a dozen tectonic plates. Plate boundaries are always faults, but not all faults are plate boundaries. The movement of the plates .
Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along plate boundaries in zones that may be anything from a few kilometres to a few hundred kilometres wide.
To watch a simulated fly-by along New Zealand's plate boundary check out this video. There are three main types of plate boundaries: Subduction zones occur when one or both of the tectonic plates are composed of oceanic crust. The denser plate is subducted underneath the less dense plate.
The plate being forced under is eventually melted and destroyed.
Earthquakes and Plate Tectonics
Where oceanic crust meets ocean crust Island arcs and oceanic trenches occur when both of the plates are made of oceanic crust.
Zones of active seafloor spreading can also occur behind the island arc, known as back-arc basins. These are often associated with submarine volcanoes. Where oceanic crust meets continental crust The denser oceanic plate is subducted, often forming a mountain range on the continent.
The Andes is an example of this type of collision.
Where continental crust meets continental crust Both continental crusts are too light to subduct so a continent-continent collision occurs, creating especially large mountain ranges.
Almost all earthquakes occur at the edges of the crustal plates. The constant bumping, grinding, and lateral movement along crustal boundaries can create sudden movements that result in earthquakes.
Each of the three types of plate boundaries—convergent, divergent, and transform—has a distinctive pattern of earthquakes. There are two kinds of convergent boundaries: A subduction boundary is marked by the oceanic crust of one plate that is being pushed downward beneath the continental or oceanic crust of another plate.
Plate Tectonic, Volcanoes and Earthquakes
A collision boundary separates two continental plates that are pushed into contact; the suture zone is the line of collision. Both types of boundaries have distinctive earthquake patterns. Earthquakes associated with a collision boundary define shallow, broad zones of seismic activity that form in complex fault systems along the suture zone. Earthquake patterns in subduction zones are more complex. As the oceanic crust begins to descend, it begins to break into blocks because of tension stress.
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Earthquakes also periodically occur as the plate continues to subduct up to a depth of about kilometers miles. Earthquakes are relatively abundant in the first kilometers miles of a subduction zone, are scarce from to kilometers to milesand then increase slightly again from to kilometers to miles.
It is possible that these deepest quakes are related to sudden mineral transformations and resultant energy releases or volume changes.