Much of the discussion on earthquake and earthquake-prediction boards occurs in near real-time - or in advance of real-time! Events which have just occurred, or are predicted to occur, are the main subjects of debate. However, my own enthusiasm for the subject is best satisfied by reading the results of research conducted on seismology in general, and on past events. For larger events, the most authoritative (and usually fascinating) papers come out at least a year after the event. Scientists use the intervening time to more fully sort out the data, come up with explanatory theories, and subject all to peer review. The Seismological Society of America just published their Special Edition on the Sept. 2004 Parkfield Quake. As I know the members of this forum are still interested in Parkfield, and Parkfield was the subject of a famous (infamous) prediction effort (and prediction is the raison d'etre of this board), I'm posting the abstracts of two of the articles in that issue below.

First-the "Introduction to the Special Issue . . ." by Ruth A. Harris and J. Ramon Arrowsmith:

The 28 September 2004 M 6.0 Parkfield earthquake, a long-anticipated event on the San Andreas fault, is the world’s best recorded earthquake to date, with state-of-the-art data obtained from geologic, geodetic, seismic, magnetic, and electrical field networks. This has allowed the preearthquake and postearthquake states of the San Andreas fault in this region to be analyzed in detail. Analyses of these data provide views into the San Andreas fault that show a complex geologic history, fault geometry, rheology, and response of the nearby region to the earthquake- induced ground movement. Although aspects of San Andreas fault zone behavior in the Parkfield region can be modeled simply over geological time frames, the Parkfield Earthquake Prediction Experiment and the 2004 Parkfield earthquake indicate that predicting the fine details of future earthquakes is still a challenge. Instead of a deterministic approach, forecasting future damaging behavior, such as that caused by strong ground motions, will likely continue to require probabilistic methods. However, the Parkfield Earthquake Prediction Experiment and the 2004 Parkfield earthquake have provided ample data to understand most of what did occur in 2004, culminating in significant scientific advances.

Next is: "The 2004 Parkfield Earthquake, the 1985 Prediction, and Characteristic Earthquakes: Lessons for the Future" by D.D. Jackson and Y.Y. Kagan:

The 1985 prediction of a characteristic magnitude 6 Parkfield earthquake was unsuccessful, since no significant event occurred in the 95% time window (1985–1993) anywhere near Parkfield. The magnitude 6 earthquake near Parkfield in 2004 failed to satisfy the prediction not just because it was late; it also differed in character from the 1985 prediction and was expectable according to a simple null hypothesis. Furthermore, the prediction was too vague in several important respects to meet the accepted definition of an earthquake prediction. An event occurring by chance and meeting the general description of the predicted one was reasonably probable. The original characteristic earthquake model has failed in comprehensive tests, yet it is still widely used. Modified versions employed in recent official seismic hazard calculations allow for interactions between segments and uncertainties in the parameters. With more adjustable parameters, the modified versions are harder to falsify. The characteristic model as applied at Parkfield and elsewhere rests largely on selected data that may be biased because they were taken out of context. We discuss implications of the 2004 event for earthquake prediction, the characteristic earthquake hypothesis, and earthquake occurrence in general.

There are a total of 26 articles in the issue, some more readable than others.

Mike Williams in Arroyo Grande, CA USA