We find evidence that at least 24 significant aftershocks, ~M≥4, occurred within the first 34 minutes following the onset of rupture in the 18 October 1989 earthquake. Only six of these very early aftershocks are contained in current listings of aftershock locations. Here we provide preliminary locations for 18 of these events. Sixteen of the 18 locations are found in the northwest portion of the mainshock rupture zone, with greatest concentration near the intersection of the San Andreas and Sargent faults. ¿The American Geophysical Union 1990