Parkfield 2004: Lessons from the Best-Recorded Earthquake in History

Andy Michael, US Geological Survey

Obtaining high-quality measurements close to a large earthquake is not easy: one has to be in the right place at the right time with the right instruments. Such a convergence happened, for the first time, when the September 28, 2004, magnitude 6, Parkfield, California, earthquake occurred on the San Andreas fault in the middle of a dense and diverse network of instruments designed by the scientists of the Parkfield Earthquake Prediction Experiment to record what occurred before, during, and after this event. The resulting data reveal aspects of the earthquake process never before seen. These data, when combined with data from a sequence of at least 6 earlier Parkfield earthquakes dating back to 1857, provide important lessons about earthquake processes, prediction, and the hazards assessments that underlie important policies such as building codes.