Why are earthquakes focused along plate margins?
What will be an ideal response?
Earthquakes are the result of plate motion: The plates move relative to each other at average speeds of a few centimeters per year. As a result of friction between the plates, there are alternating periods of stasis (during which stresses build) and periods of movement (when they are released) both at the plate boundary and near the surface. (Seismic and satellite measurements indicate that at greater depths or farther from the plate boundary, the motions are more continuous.) After a period of stasis, pent-up energy is released suddenly as the plates jump past each other, causing earthquakes. As predicted, the distribution of earthquakes at Earth's surface follows plate boundaries quite closely
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