The place where three plates of the Earth’s lithosphere join. The boundaries of the plate junctions may be rifts (R), subduction zones (T), or transform faults (F). Triple junctions may be of 16 different types, such as RRR, TTT, FFF, RRT, RRF, TTR, TTF, FFR, FFT, or RTF; see Figure T-16. A triple junction is stable when the relative motions of the three plates and the azimuths of their boundaries are such that the configuration of the junction does not change with time, although the location of the triple junction may move along one of the boundaries. An unstable triple junction evolves to a different geometry.