San Francisco Pacific Ocean San Francisco Bay GEOLOGY OF SAN FRANCISCO, CALIFORNIA United States of America Geology of the Cities of the World Series Association Engineering Geologists Geology of Cities of the World Series Geology of San Francisco, California, United States of America Issued to registrants at the 61st Annual Meeting of the Association of Environmental & Engineering Geologists and 13th International Association of Environmental & Engineering Geologists Congress in San Francisco, CA – September 16 through 22, 2018. Editors: Kenneth A. Johnson, PhD, CEG, PE WSP USA, San Francisco, CA Greg W. Bartow, CHg, CEG California State Parks, Sacramento, CA Contributing Authors: John Baldwin, Greg W. Bartow, Peter Dartnell, George Ford, Jeffrey A. Gilman, Robert Givler, Sally Goodin, Russell W. Graymer, H. Gary Greene, Kenneth A. Johnson, Samuel Y. Johnson, Darrell Klingman, Keith L. Knudsen, William Lettis, William E. Motzer, Dorinda Shipman, Lori A. Simpson, Philip J. Stuecheli, and Raymond Sullivan. It is hard to be unaware of the earth in San Francisco (Wahrhaftig, 1984). A generous grant from the AEG Foundation, Robert F. Legget Fund, helped make this publication possible. Founded in 1993, the Robert F. Legget Fund of the AEG foundation supports publications and public outreach in engineering geology and environmental geology that serve as information resources for the professional practitioner, students, faculty, and the public. The fund also supports education about the interactions between the works of mankind and the geologic environment. Cover Plate: European Space Agency i Table of Contents PREFACE v ABSTRACT 1 INTRODUCTION 1 Geographic Setting . 1 Climate . 6 History and Founding . 6 Native Americans . 6 European Founding of San Francisco . 7 Gold Rush and Its Impact to San Francisco . 11 Between the Gold Rush and the 1906 Earthquake . 13 Quarries in San Francisco . 16 1906 Earthquake . 19 Rebuilding after the 1906 Earthquake and Fire . 23 Panama-Pacific International Exposition . 24 World War II: Military Base Expansion . 24 Post-WWII High-Rise Building Boom: The Manhattanization of San Francisco . 25 San Francisco in the Future: Major New Transit Projects on the Horizon . 25 GEOLOGY AND GEOLOGIC HISTORY 30 Overview of the Geology of the San Francisco Bay Region . 30 Introduction: The Road to Accretion . 30 Geologic Overview of the San Francisco Bay Region . 33 Geology of San Francisco . 41 San Francisco Basement Complex Rocks . 41 Geologic Structures in San Francisco . 51 Tertiary Overlap Sequences . 51 Quaternary Deposits in San Francisco . 52 San Francisco’s Offshore Geology . 58 Geologic History of San Francisco . 61 Rocks Passing Through . 61 Rocks From Somewhere Else . 62 Neogene Paleogeography . 64 GEOTECHNICAL AND ENGINEERING GEOLOGY CHARACTERISTICS OF GEOLOGIC UNITS 67 Artificial Fill . 67 Eolian Deposits and Dune Sands . 67 Young Bay Mud . 68 Colma Foundation . 68 Index Properties . 68 Hydraulic Conductivity . 68 General Engineering Practice . 69 Yerba Buena Mud (Old Bay Deposits) . 69 Index Properties . 69 Relative Density and Consistency . 69 Hydraulic Conductivity . 69 Franciscan Complex Rocks . 69 Quarries . 70 ii Rock Falls and Slope Stability . 70 GEOLOGIC ASPECTS OF NATURAL HAZARDS 70 Earthquake Hazards . 70 San Andreas Fault . 71 Hayward–Rodgers Creek Fault . 78 San Gregorio Fault . 79 Calaveras Fault . 80 Faults of San Francisco . 81 Liquefaction and Lateral Spreading . 82 WATER RESOURCES 84 San Francisco’s Water Supply . 84 Early Years . 84 Post Gold Rush . 84 Search for a Sierra Source . 84 Sunset Well Field . 86 Hetch Hetchy Regional Water System . 87 Water System Improvement Program . 87 Auxiliary Water Supply System . 90 Diversification of Water Supplies . 92 Local Groundwater . 92 Non-Potable Water . 92 Recycled Water . 92 San Francisco Creeks and Lakes . 93 Lobos Creek . 93 Mountain Lake . 93 Lake Merced . 93 Vista Grande Drainage Basin Improvement Project . 95 Groundwater . 95 Westside Groundwater Basin . 95 Lobos Groundwater Basin . 102 Marina Groundwater Basin . 102 Visitacion Valley Groundwater Basin . 103 Downtown Groundwater Basin . 103 Islais Valley Groundwater Basin . 105 South San Francisco Groundwater Basin . 105 ENVIRONMENTAL CONCERNS 106 Regulatory Setting . 106 GeoTracker . 106 Maher Ordinance . 106 Hunters Point Naval Shipyard . 108 Cleanup Program at the Shipyard . ..