Earthquakes
Crustal plater do not gilde smoothly past one another. Instead, tremendous friction exists along plat bound-aries. The stress (a force) of plate motion builds sirain (a deformation) in the rocks until friction is overcome and the sides along plate boundaries or fault lines suddenly break loose. The two sides of the fault plane then lurch into new positions, moving from centimeters to several meters, and release enormous amounts of seismic energy into the surrounding crust. This energy radiates through- out the plnet, diminishing with distance, but sufficient enough to register on instruments worldwide.