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generate large earthquake loads at the Forward Landfill. An MPE moment magnitude (Mw) 6.4 earthquake on the Great Valley fault would generate a PGHA of approximately 0.098; an MCE MW 6.7 event on the Great Valley fault would generate a PHGA of approximately 0.13g. While the Great Valley fault was calculated to yield the highest PHGA, the duration of earthquake-induced ground shaking would be longest for the San Andreas fault system. The MPE and MCE on the San Andreas fault system are characterized by the same MW 7.9 event at a distance of 70 miles (112 km). As shown on Table 4, such a large-magnitude distant event is calculated to induce strong ground shaking that could last 45.4 seconds. Given the relatively small difference in the estimated bedrock PHGA and the relatively large difference in estimated Dy Geosyntec concluded that the M,v 7.9 event on the San Andreas fault system could be the most damaging earthquake for the Forward Landfill. Accordingly, the MW 7.9 event on the San Andreas fault system should be considered for evaluation of both MPE and MCE design ground motions at the Forward Landfill along with the appropriate M,,event on the Great Valley blind thrust system. A target acceleration response spectral envelope was developed by Geosyntec for each of the MCE/MPE candidate events using the median and 84" percentile acceleration response spectra evaluated using the Abrahamson and Silva [19971 attenuation model. Based upon the target significant duration of strong ground shaking and acceleration response spectral envelope for each candidate event, the following four time histories were selected to represent potential ground motions at a hypothetical bedrock outcrop at the site: • the 270-degree component of the Saratoga-Aloha Avenue record from the M,, 6.9 Loma Prieta earthquake, scaled to either 0.19 g to represent the MCE or to 0.13 g to represent the MPE; • the 315-degree component of the Santa Teresa Hills record from the MW 6.9 Loma Prieta earthquake, scaled to either 0.19 g to represent the MCE or to 0.13 g to represent the MPE; • the 360-degree component of the Corralitos-Eureka Canyon Road record from the MW 6.9 Loma Prieta earthquake, scaled to either 0.19 g to represent the MCE or to 0.13 g to represent the MPE; and Forward Landfill)TD 3-6 L:\Allied\2000.193\Reports\jtd:Sec-3.0:05/21/02 BRYAN A.BTIRRAT&.ASSOCIATES