Geology of Los Angeles, California, United States of America

The City of Los Angeles is located on the east edge of the Pacific Plate, within the wide transform boundary zone with the North American Plate and near the big bend in the San Andreas fault. Situated just south of this restraining bend, the city is within the Western Transverse Ranges which are undergoing transpressional uplift along active thrust faults. The city has experienced and mitigated the effects of earthquakes on the San Andreas and local faults, floods, fires, droughts, landslides and debris flows. The natural resources of Los Angeles include vast oil and gas deposits and the La Brea Tar Pits, an important Pleistocene fossil locality. Urbanization over and tunneling through both abandoned and active oil and gas fields have encountered hazardous conditions. Seepage of hazardous gasses has caused explosions within the city and as a result Los Angeles established methane mitigation requirements for construction in methane hazard zones. Los Angeles has been aggressive in addressing issues of air, soil and water pollution control. A master plan for solid waste management has been implemented, regulating the siting and operation of landfills. Local sources of drinking water are inadequate to support the population. Importation of drinking water via three aqueducts has fueled the city's growth and agricultural prosperity. The practice of engineering and environmental geology has been greatly influenced by laws, practices and policies that were started in or influenced by the City of Los Angeles. These include the 1915 Los Angeles Flood Control Act, 1929 California Dam Safety Act, 1958 Engineering Geologists Qualifications Board, 1933 Field Act, 1972 Alquist-Priolo Act, 1975 Seismic Safety Act, 1990 Hazards Mapping Act, and modifications to the Uniform Building Code for seismic safety.