Earthquake prediction lessons from Parkfield Experiment

In 1985, the National Earthquake Prediction Evaluation Council (NEPEC), and later its California counterpart (CEPEC), approved an earthquake prediction for the first time. This was the Bakun and Lindh [1985] forecast, with 95% confidence, that an M = 5.5 to 6 earthquake would rupture along the San Andreas fault near the town of Parkfield before 1993. This forecast was an important factor in selecting the Parkfield area for a major geophysical and geological monitoring study. The experiments installed there are aimed at producing a better understanding of the earthquake generation process and earthquake effects, gaining experience with real-time monitoring of a variety of geophysical data, and, if possible, making a short-term prediction of the future earthquake. Twenty-eight different observational networks now exist in the Parkfield area. The forecast also generated interest that led researchers to reexamine past Parkfield earthquakes with current knowledge and to develop new models of the earthquake cycle.