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results in a low potential for large area or focal ground subsidence due <br />to earthquakes. <br />Soil liquefaction is the phenomenon in which water - saturated, cohesion - <br />less soil temporarily loses its strength when subjected to dynamic forces. <br />Soils most vulnerable to liquefaction are those that are composed of <br />saturated sands, in a loose to medium -dense condition, in areas where <br />the water table is less than 20 feet deep. The probability of <br />liquefaction occurring in Santa Ana is relatively low, given the type of <br />earthquake expected and the distance to active faults. <br />Moderate to high potential subsidence and liquefaction areas within the <br />subject segment of Bristol Street are shown on Figure 10, following. <br />Only the extreme northerly portion is considered subject to a potential <br />subsidence hazard. Most of the south half of the study area, between <br />McFadden Avenue and Warner Avenue, is in an area classified as <br />within the highest potential liquefaction area. Between McFadden <br />Avenue and First Street, the liquefaction hazard potential is considered <br />moderate. From First Street north to Memory Lane, liquefaction <br />potential is considered slight. <br />3. S_ oll5 no <br />Within the project area, there are no instances of undisturbed, natural <br />soils. All surface areas have been modified or covered, due to <br />construction activities or due to the planting of urban landscape <br />materials. The soil types found throughout the project area are <br />important in terms of their characteristics which would support or <br />constrain further urban development and' redevelopment, including the <br />proposed street widening. <br />The distribution of soil types found within the study area is shown on <br />Figure 11, following. As described in the Soil Survey for this area, <br />prepared by the U.S. Soil Conservation Service, these soils have the <br />following characteristics: <br />Chin Silty Clay Loam—Drained. Nearly level, on large alluvial fan. <br />Moderately alkaline and calcareous throughout. If soil is bare, runoff is <br />slow and erosion hazard slight. This soil is drained and the water table <br />is more than 60 inches below the surface. The effective rooting depth <br />is 60 inches or more. Depth to bedrock exceeds 50 inches. Moderate <br />shrink -swell potential. Low risk of corrosion to concrete; moderate - <br />High risk of corrosion to uncoated steel, depending on depth. <br />III -4 <br />