Scenario Response and Restoration of Los Angeles Water System to a Magnitude 7.8 San Andreas Fault Earthquake

This paper describes the potential impacts of a magnitude 7.8 San Andreas Fault earthquake scenario to three major aqueducts providing domestic and industrial water supply to Southern California and the Los Angeles Department of Water and Power (LADWP) water transmission and distribution system. The aqueducts will sustain significant damage, and restoration of water flow to different lines are estimated to take between 4 and 18 months. Local emergency water supplies may not be sufficient to match the duration of aqueduct repairs, requiring severe water rationing. Large ground motions cause nearly 2,700 damage locations in the LADWP transmission and distribution pipe networks. Due to the large number of leaking pipes, system serviceability declines rapidly, resulting in 66% of unmet water demand after 24 hrs. Restoration of water flows to all customers may take up to several months and restoration of pre-earthquake water demand may take a year. The earthquake scenario estimates a super conflagration in a densely populated area of Los Angeles, where water serviceability is no more than 31%, causing difficulties for firefighting. Business interruptions due to long term water rationing may affect the regional economy greater than previously anticipated. Results of this study show how critical it is for all water agencies to prepare for a great San Andreas Fault earthquake.