The Pinto Mountain Fault runs east–west across the Mojave Desert of southern California near Twentynine Palms and the northern edge of Joshua Tree National Park. It is a left-lateral strike-slip fault, unusual in a region dominated by right-lateral faults, and it intersects the major right-lateral faults of the eastern California shear zone.
Its east–west orientation lets it act as a transfer structure between the northwest-trending faults that carry most of the region's plate-boundary motion. Offset desert washes and ridges mark its long-term left-lateral slip across the arid landscape.
No great earthquake has been directly recorded on the Pinto Mountain Fault, but it lies near faults that produced the 1992 Landers and 1999 Hector Mine earthquakes. Studies suggest it interacts with those ruptures and is capable of moderate to strong events of its own.