Three tectonic plates meet at triple junctions . The combinations of crustal type and of motion along the three margins determine the sequence of events at the triangular interplate sites. Activity within plates includes transmission of hot spot magmas and fluids as well as intraplate offset motions. Intraplate scale Crustal blocks also move with respect to one another within plates. Fractures, planes of breakage, may separate portions of crust.
Infinitesimal movement occurs at joints.
Parallel movement along fractures defines fault planes. Such motion exhibits similarities to motion between plates. Dip-slip motion occurs on faults oriented at an angle oblique to the horizontal surface of the earth. Strike-slip or transfer faults define planes along which crustal blocks slide laterally past one another. Slip occurs on faults to release the strain accumulated by the stress of crustal motion.