which parameter was a precursor to the 2004 parkfield earthquake
Earthquake prediction 1993 came, and passed, without fulfillment. Eventually there was an M 6.0 earthquake on the Parkfield segment of the fault, on 28 September 2004, but without forewarning or obvious precursors.[156] While the experiment in catching an earthquake is considered by many scientists to have been successful,[157] the prediction was unsuccessful in that the eventual event was a decade late.[158]