Understanding Earthquakes

Sophisticated numerical models can reproduce a wide range of seismic activity at the Parkfield segment of the San Andreas Fault. Progress in understanding the mechanics of earthquakes has come from improvements in data collection, laboratory experiments, and theory, allowing numerical simulations that are ever more “Earthlike” in character (1). On page 707 of this issue, Barbot et al. (2) compare sophisticated dynamical simulations to a sequence of well-recorded moment magnitude (Mw) 6.0 earthquakes along the Parkfield segment of the San Andreas Fault. Parkfield was the site of the only official earthquake forecast in the United States, with an intensive effort undertaken to obtain high-resolution data near a moderate-sized shock (3). Although the earthquake failed to occur within the expected time window, it did provide a wealth of data that can be compared to the predictions of dynamical models (4).

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