to the seething, ceaseless dynamics of the great heat engine that is the earth's interior. The next major earthquake in California, "The Big One" natives call it cavalierly, is as inevitable a natural phenomenon as the sunrise, though unfortunately not as predictable. When it arrives, the dead could well number in the tens of thousands, a scenario that charges modern earthquake scientists, called seismologists, with a mission and a sense of purpose far beyond the pursuit of pure science.


In 1992 the American seismological community was galvanized and challenged by several dramatic events. On the morning of June 28, a meeting attended by many of America's most eminent seismologists was about to get under way at the University of California-Santa Cruz. Their purpose was to review and begin to evaluate a U.S. Geological Survey (USGS)-run project nearly a decade in the running: The Parkfield Earthquake Prediction Experiment. For reasons that will be explained shortly, some seismologists were virtually "certain" (in statistical terms they expressed a 95 percent confidence) that a major quake was due to occur near a small town in Central California before too many years. Writing in Science in 1985, Bill Bakun and Al Lindh of the USGS predicted that an earthquake would occur before 1993 near Parkfield. As of June 1992 the predicted quake had not arrived. But the project had focused on that particular section of the San Andreas fault a level of scientific attention and study that was unprecedented in America; many valuable insights had been collected, and the scientists were meeting to consider these and other implications of the Parkfield experience.

Then on the morning the Parkfield meeting was to convene, the earth began to shake. The quake was not the magnitude (M) 6 earthquake predicted for Parkfield, however, but one many times larger (see the Box on p. 158), an M 7.3 quake emanating from a small desert community called Landers, dozens of miles to the south. The Landers quake relegated to a distant second place (in terms of the magnitude of energy released) the state's most famous recent quake—the Loma Prieta M 7.1 quake in 1989, which, as the World Series telecast had just begun, millions experienced vividly via television. As California's largest quake in 40 years, Landers was big news to scientists not because of its devastation—fortunately,

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