EARTHQUAKES Fifth Edition Bruce A. Bolt University of California, Berkeley DS W. H. Freeman and Company New York
Preface xi What We Feel in an Earthquake 1 The 1906 Eye-Opening San Francisco Earthquake 3 BOX 1.1: The 1906 San Francisco Earthquake Centennial 5 The 1989 Santa Cruz Mountains (Loma Prieta) Earthquake, California 10 Two Huge Alaska Earthquakes: 1964 and 2002 14 Types of Seismic Waves in Earthquake Shaking 19 A "Big One" in Taiwan, 1999 24 Where Earthquakes Occur 28 Why Earthquakes? ' 29 Earthquakes in Past Times 31 Observatories to Study Earthquakes 33 The Global Mosaic of Earthquakes 34 Depths of Earthquake Foci 39 Sakhalin, Russia, Disaster, 1995 42 Surprise Seismicity in Upper Egypt 44 Moonquakes and Marsquakes 47 APPLIED SEISMOLOGY BOX 2.1: Mystery of the Great \ Tunguska UFO, 1908, Siberia 50 3 Faults in the Earth 52 Types of Geological Faults 53 The 1891 Mino-Owari (Nobi) Earthquake, Japan 59 The 1979 Imperial Valley Earthquake, California 61 A Recent Japanese Example, Kobe 1995 62 The Tragedy of the 1988 Armenian Earthquake 64 The 1990 Philippine Fault Rupture 67 A Further Unzipping: 1999, Kocaeli, Turkey 71 Fault Slippage and Fault Gouge 73 (V) The Causes of Earthquakes 78 Types of Earthquakes 79 Geodetic Surveying and the Slow Buildup of Energy 82
APPLIED SEISMOLOGY BOX 4.1: Impacts of the World Trade Center Collapse, September 11, 2001 83 Elastic Rebound 88 The Effect of Water on Rocks Beneath the Surface 90 Reservoir-Triggered Earthquakes and Dam Safety: Oroville, California,1975 94 What Produces Seismic Waves? 101 BOX 4.2: Method of Obtaining Direction of Faulting from P-Wave Directions on Seismograms 104 Twin Thrust Sources: 1971 San Fernando and 1994 Northridge 106 Measuring Earthquakes 108 Sensitive and Strong-Motion Seismographs 109 How to Understand Seismograms 114 How to Locate an Earthquake 116 BOX 5.1: Sample Calculation of the Location of the Epicenter of an Earthquake (Near Oroville, August 1975) 118 APPLIED SEISMOLOGY BOX 5.2: Tragedy of the Russian Kursk Submarine 120 The Digital Revolution-The Modern Earthquake Telescope 122 Close to the Fault Source 123 BOX 5.3: Imprint of a Moving Fault Rupture 124 Exploring Inside the Earth 128 Earthquake Waves Through the Interior 129 Seismic-Wave Probes \ 131 Interpretations of Seismograms 133 Interior Earth Structure 135 Illuminating the Innermost Core 136 Fine Mapping of Deep Earth Structure 138 Earthquakes and Plate Tectonics 142 Driving Forces in the Earth 143 The Plate Conveyer-Belt Solution 146 Explanation of Inter- and Intraplate Earthquakes 150 Predictions Using the Plate Tectonic Theory 153 The 1960 and 1985 Chile Interplate Earthquakes 155 The Size of an Earthquake 158 Intensity of Shaking 159 How to Calculate Earthquake Instrumental Magnitude 163
( j x BOX 8.1: Example of the Calculation of the Richter Magnitude (M L )of a Local Earthquake 165 Energy in Earthquakes 167 The Seismic Moment Magnitude 168 A Detective Story: Nuclear Explosions or Natural Earthquakes? 171 APPLIED SEISMOLOGY BOX 8.2: Seismic Mystery in Australia: Earthquake, Meteorite, or Nuclear Blast? 173 Acceleration of Ground Shaking 174 Landers, 1992: The Largest U.S. Earthquake in 28 Years 177 Upthrow 179 Volcanoes, Tsunamis, and Earthquakes 182 Eruptions in Hawaii 185 Volcanic Hazards 187 Explosion of Mount Saint Helens, 1980 189 Mammoth Lakes Earthquake Swarm, California 192 Tsunamis 195 BOX 9.1: Notable Tsunamis of the World 197 BOX 9.2: Properties of a Tsunami 201 Tsunami Alerts: The 1993 Hokkaido Disaster 203 Tragedy at Crescent City, California, 1964 206 Atlantis and Santorini 207 10) Events That Precede an Earthquake 210 Efforts at Earthquake Forecasting 211 BOX 10.1: Types of Socioeconomic Impacts and Adjustments to an Earthquake Prediction 216 Clues for Recognizing Impending Earthquakes 217 BOX 10.2: Suggested Physical Clues for Earthquake Prediction 219 Earthquake Prediction in China 222 Fossil Earthquakes 227 The Cascadia Subduction Zone in the Northwest United States 230 Silent Earthquakes 234 The Parkfield, California, Earthquake Prediction: Failed but Postponed 235 Calculating the Probability of an Earthquake 237 BOX 10.3: Probability of Seismicity for California 239 APPLIED SEISMOLOGY BOX 10.4: Brightness and Shadow: Predicting Earthquake Patterns 240
Contents Dangers from Earthquakes 244 Types of Hazards 245 BOX 11.1: The Main Earthquake Hazards 246 Liquefying Wet Sand 249 Self-Protection in an Earthquake 251 BOX 11.2: Personal Protection in an Earthquake 252 The 1983 Coalinga, California, Earthquake 256 A Study in Hazard: Chi-Chi, Taiwan, 1999 258 Steps to Reduce Hazards to Homes 260 Help from Earthquake Insurance 263 Reducing Earthquake Risk 268 Improvements in Planning and Zoning 269 Collapse of Unreinforced Masonry: Newcastle, Australia, 1989 274 The Mexico Earthquake of September 19, 1985 278 Major Engineered Structures and Earthquake Risk 281 BOX 12.1: Seismicity Risk Studies for a Particular Site 284 Safe Operation of Hospitals and Schools 285 The Deadliest Intraplate Earthquake, India 2001 289 The Loss of Art: Assisi, September and October 1997 290 The 1989 Loma Prieta and 1994 Northridge Earthquakes Revisited 293 Emergency Warning Systems: "Shake Maps" 298 What Is Acceptable Risk? 299 Appendices 304 A: World Earthquakes and Seismicity Rates \ 304 B: Important Earthquakes of the United States and Canada 313 C: Abridged Modified Mercalli Intensity Scale 327 D: Geologic Time Scale 330 E: Conversion Tables 332 F: How to Determine Fault Planes from First Motions 334 G: Sample Calculations of Magnitudes, Moment, and Energy of an Earthquake 338 H: The Elements of Wave Motion 340 I: Propagation of Elastic Waves 343 An Earthquake Quiz 344 Answers to Quiz 350 Glossary 352 Further Reading 359 Internet Resources 362 Index 366