Stress in Earth's Crust
Key Questions
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Tension is the state of being under stress, or more specifically in this case when the Earth’s crust is under stress.
Tension often occurs along continental plates and is a strong force which drives plates apart under the ocean as well. Where ever tension occurs, the crust begins to crumble and weaken, often causing fault lines, almost cracks in the crust.
Generally tension occurs by pulling two parts of the crust apart, resulting in an area of lower elevation, possibly even a valley. IF you can imagine this, you can think of tension almost like pulling apart silly putty, or gum. When you pull at both ends, the middle sections become stretched out and weak, often breaking if stretched too far. Tension affects the crust in the same way.
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Shearing is a force tending to cause deformation of a material by slippage along a plane or planes(areas) parallel to the imposed stress. The resultant shear creates a large effect in nature, being closely related to the downslope movement of earth materials, and to earthquakes.
Ultimately, shearing can happen anywhere there is enough pressure being exerted on the crust. However, the most likely location for a shear is a fault line.