Download Notebook #3 Lithospheric Plates gt

Lithospheric Plates
Notebook #3
February 25, 2016
8.E. 5B.2 Following these notes you will be able to construct explanations of how forces inside Earth
result in earthquakes and volcanoes.
* Convection currents in the mantle result in the movement of lithospheric plates.
* The motion and interactions of the plates can create patterns in the location of volcanoes and
earthquakes that result along the plate boundaries
* The resulting activity that happens along the plate boundaries depends on the type of plate boundary
being created (divergent, convergent, and transform) and the forces associated with those boundaries
(compression, tension, and shearing)
Lithospheric Plate Motion and Seismic Activity
* Earthquakes occur along plate boundaries where tectonic forces result in the formation of faults and
the buildup of pressure.
* When this built up pressure is released, an earthquake results along this fault line.
* Earthquakes can also occur along faults:
- Scientists can specifically identify the type of boundary and fault that occurs along the edges of
the plates by examining plate boundary maps
- Scientists can also use seismic data to understand the ways in which the plates are moving and
the relationship between seismic activity and lithospheric plate motion.
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Lithospheric Plate Motion and Volcanic Activity
* There is scientific data supporting abundant volcanism occurrences at divergent and convergent plate
boundaries and a lack of volcanism associated with transform plate boundaries.
- Volcanic activity at divergent plate boundaries occurs as the plates pull apart which allows
magma to fill the rift zone between the separating plates.
- Volcanic activity at convergent plate boundaries occurs as the two plates converge on one
another. The leading edge of the subducted plate melts and rises through the overlying crust resulting
in the formation of a volcanic chain of mountains. The most volcanically active belt on Earth is known as
the Ring of Fire, a region of volcanic activity that happens at subduction zones surrounding the Pacific
Ocean.
-Volcanic eruptions are constructive in that they add new rock to existing land and form new
islands. Volcanic eruptions can be destructive when an eruption is explosive and changes the landscape
of and around the volcano.
- Magma that reaches Earth's surface is knows as lava.
Convergent plate boundary forms volcanic activity
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Divergent plate boundary forms volcanic activity
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Ring of Fire
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The specific types of volcanism that happens at divergent and convergent plate boundaries are called
spreading center volcanism and subduction zone volcanism.
* Intraplate volcanism is another term to describe the presence of volcanic activity over hot spots.
* Specific surface features created from lithospheric plate motion include the Mid-Atlantic Ridge,
Mariana trench, and the Aleutian trench.
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