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We 0115103M�� <br />�:• �r r <br />MOOR. — <br />As shown on the U.S.G.S. Anaheim and Newport Beach Quadrangle <br />Maps (See Figure 9, following), the project area is nearly flat. A very <br />slight gradient exists, sloping northwesterly to southwesterly, between <br />Memory Lane and Edinger Avenue, then shifting slightly to a more <br />north to south slope to Warner Avenue. The elevation at Bristol Street <br />and Memory Lane is about 120 feet above sea level (ASL), while the <br />elevation at Bristol Street and Warner Avenue is about 45 feet ASL. <br />This 75 -foot fall across the total 20,600 foot long roadway segment <br />accounts for a fairly uniform average slope of just under four - tenths of <br />one percent. <br />No roadside embankments or other notabie topographic features exist <br />within the project area. <br />2. Geolopy <br />No earthquake faults, whether active, potentially active or inactive, are <br />known to exist in the City of Santa Ana. There are, however, two <br />major faults in close proximity to the City: the Newport- Inglewood <br />Fault, some 8 miles to the west /southwest; and the Whittier- Elsinore <br />Fault, some 12 miles to the northeast. Other fault zones, including the <br />San Andreas and the Raymond faults, are located 40 and 30 miles <br />away, respectively. Susce it is the closest fault zone, the Newport- <br />Inglewood Fault is considered the most likely source of earthquake - <br />related seismic hazards. Seismic parameters for each of the active <br />faults within a 40 mile radius of Santa Ana are illustrated in Table 6, <br />following. <br />Historically, earthquake- associated geologic hazards have not been <br />significant in Santa Ana. Rather, subsidence and liquefaction have <br />been the primary geotechnical problems. <br />Subsidence is the general lowering of the ground surface over a large <br />area. Area subsidence has occurred within various parts of the City, <br />generally attributed to lowering of ground water levels and the <br />settlement and oxidation of peat. More localized or focal subsidence <br />can occur as a result of earthquake motion. The potential for <br />subsidence is largely dependent on the magnitude, duration and <br />frequency of the earthquake energy waves. The design earthquake <br />(maximum probable earthquake) for Santa Ana is one of a long - period, <br />rolling motion, rather than intensive high frequency shaking. This <br />7 5 C 172 <br />