2010-025 - Create the Urban Neighborhood Land Use Designation

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LAND USE ELEMENT Ground Motion - The intensity of ground shaking ac a given location depends primarily on an earthyuake's magnitude, distance from the source (epicenter), fault characteristics, and the characteristics of soils, and geolo}ry of the impacted area. i\Qost emergency preparedness planners and geological scientists expect a major damaging earthquake within the next 20 years. "I'he greatest potential For earthquake damage is expected to come from a large earthquake along the Newporz-Inglewood f=ault. A Magnitude 7 earthquake on the fault would be expected co cause significant damage regionally. Liquefaction -The City of Santa Ana is located in an area with relatively high groundwater. In the event ofa major earthquake, liquefaction within the City is generally not considered to be a hazard if the water cable is deeper than 50 fete, except for areas along drainage channels with shallow gruundwater. "I~hcre are some areas in the City with groundwater depths of less than SO feet. "}'he south-central portions of the City (shown in Exhibit A-7), and those areas along the Santa Ana River contain soils which are susceptible to liquefaction. Soil Subsidence and Settling -Soils in portions of the Cicy along the Santa Ana River may be subject to settling since most of these areas contain unconsolidace~d and recent alluvium. Subsidence and swelling, and ground settlement are generally due to the withdrawal offluids From the earth such as oil or water. Groundwater pumping may also lead to land subsidence. Subsidence hazards in Santa Ana arc shown in ExhibitA-S. FLOOD HAZARDS "I'he Santa Ana. River is the major drainage channel flowing through the City and many ofthe major storm drains in the City, are (directly or indirectly) connected to it.'1'hc Santa Ana River is slated to undergo substantial modification, and will be fully lined where it passes through. the City upon project completion. Major segments of the Santa Ana River have been modified with high earthen levees to minimiz.c flood damage to the surrounding area. Santiago Creek is the main tributary to the Santa Ana River. T'he creek joins the Santa Ana 12ivcr just south ofGardcn Grove I3oulevard. Areas ofthc City located within 100 and 500-year Rood plains are identified in Exhibit A-~. S,..yh 1 M1. '~.,'.F 1 S Resolution No. 2010-025 ~ I Page 84 of 107 ~ ,~-~,~,, i ``j~,,•`, f ~ '~„-_. CITY OF SANTA ANA GENERAL PLAN A-d l