The Loma Prieta (LP) compressional bend of the San Andreas fault zone (SAF) appears to be multi-stranded and vertically segmented; thus, faults in this segment other than the one that ruptured in 1989 may: 1) be the source of prior large events associated with this portion of the SAF and 2) be highly stressed after the 1989 LP event. The fault that ruptured in 1989 was remarkably aseismic during the preceding 20 years; seismicity occurred on some of the neighboring faults of the system, but others remained aseismic. The Lake Elsman burst of seismicity within 1.6 years of the main shock is on a set of secondary faults within the foot-wall of the rupture. The shallow (≤5 km) portion of the SAF, morphologically and structurally characterized as steep and predominantly strike-slip, and the imbricate thrust zone to the northeast were also quiescent. These upper crustal faults may partition the oblique motion accomplished by LP-like ruptures in the lower crust into fault-parallel (transcurrence) and fault-normal motion (convergence), respectively. While the overall level of seismicity in the region around LP increased over the 20 years before 1989, the level of seismicity (number of events) on the creeping portion of the SAF next to the LP segment decreased. Moreover, the level of background seismicity on this and other fault segments varied dramatically, both up and down, in conjunction with major regional earthquakes on other segments. Thus, improved models for precursory patterns of seismicity should account for mechanistically more realistic changes than simple seismicity increase or decrease everywhere around an impending rupture. ¿ American Geophysical Union 1990