24, 1987 (M=6.6)
The Superstition Hills fault ruptured in its entirety on November 24, 1987. The total amount of separation substantially increased by persistent afterslip in the months after the main shock; in fact, the rate of afterslip was so great on the south half of the surface break as to leave open the possibility that all of its displacement occurred as afterslip. The earthquake was preceded by a major foreshock (M=6.2), on a conjugate, northeast-trending, left-lateral strike-slip fault that intersected the Superstition Hills fault at the main-shock epicenter. The surface-faulting pattern of the entire sequence was particularly remarkable for the occurrence of numerous breaks on other conjugate faults in the north quadrant around the main break (see Hanks and Allen, 1989).