Waiting for Parkfield to quake

After dark on November 16, a media van collided with a cow while driving through earthquake country near Parkfield, Calif. That may have been the most damaging incident to occur during the 72‐hour earthquake alert issued, on November 14, by the state's Office of Emergency Services (OES). Officials issued the Level A alert—meaning there was a one in three chance of a magnitude‐6 quake within 3 days—following a 4.8‐magnitude quake in the town of Parkfield, on the San Andreas fault. The probability of a bigger quake dies off rapidly with time. And, although the anticipated tremor never came, seismologists wrote another chapter in earthquake analysis and prediction in this seismically perilous state.