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analyses and depict the critical failure surfaces resulting from search routines incorporated in the stability analysis program. Similar to the discussion presented in our letter dated July 28, 1993, as the level of the tailings within the impoundment rise, the factor of safety for these potential upstream slope failures will increase. During earthquake shaking and following dissipation of excess pore water pressures generated during liquefaction particularly the soil column can settle. Tokimatsu and Seed (1984) present a method for estimating earthquake induced settlements which is based on empirical data from a number of sites subjected to large earthquakes. The empirical data summarized in this paper can be utilized to provide an estimate of the settlements which may occur beneath the dam raise due to an earthquake. Following dissipation of pore pressures generated during liquefaction, volumetric strains of 1 to 10 percent have been observed for a M=7.5 earthquake. The same magnitude earthquakes have produced strains of zero to 0.5 percent for saturated sands which did not liquefy and very low strains for non-saturated granular deposits. If the volumetric strain is assumed to occur only in the vertical direction, then settlements due to an earthquake can be estimated. For the San Luis Project the potentially liquefiable zone will be conservatively estimated to undergo a strain of 7.5 gercent during and following the earthquake and the remainder of the tailings a strain of 0.5 percent. Beneath the upstream toe of the raise there is approximately 3 ft of potentially liquefiable tailings and 26 ft of non-saturated tailings. Assuming the strains occur only in the vertical plane the resulting settlement at the upstream toe of the raise would be 4.3 inches. Beneath the upstream edge of the raise crest, there is approximately 5 ft of non- saturated tailings. With a vertical strain of 0.5 percent, the crest would settle only 0.3 inches. The resulting differential settlement would be 4 inches over a distance of 70 ft which the structure is capable of tolerating. Based on the results of the additional stability analyses which were conducted using steady-state strengths for the liquefiable tailings and inertia forces and the conservative estimates of seismically induced settlements, the Division's request that BMRI commit to providing an additional 4 ft of freeboard with the raise is not warranted.