Hi All. Here is a statement by Robert Geller. Click on the link below and arrow just a little over half way down to find where this statement may be read in its entirety. Take Care...Don in creepy town.

Do any such precursors exist? Obviously, yes: foreshocks for one.
A second possible definition of "precursors," is physical phenomena that could, at least in principle, have been identified, in advance, as precursors of some particular large earthquake with enough reliability and accuracy to specify the magnitude, time, and hypocenter of the earthquake so that an alarm could have been issued. (Researchers adopting this definition are implicitly taking a highly classical view of large earthquakes as deterministic phenomena which have a long and predetermined "preparatory process.") Do any such precursors exist? In general, with the important quasi-exception of foreshocks, discussed below, I would say the answer is a definite "no."
Just like the earthquake prediction debate as a whole, the debate over precursors suffers greatly from a lack of clear definitions, and also from a lack of rigorous scientific methodology. Almost every conceivable physical phenomenon: geodetic deformation, electromagnetic signals, water levels in wells, animal behavior, etc., has been suggested as an earthquake precursor. Persons making precursor claims frequently claim that they are in an immediate position to make predictions that could be useful for society. Some of these workers even issue vague predictions directly to the mass media. How can we sort this confusing situation out?
Let us begin by considering the example of foreshocks. We know that many earthquakes are preceded by foreshocks, but it appears at present that there is no reliable way to identify any particular event in advance as a foreshock of a specific impending large earthquake. Furthermore, many large earthquakes are not preceded by foreshocks. As will be discussed by several talks at the workshop, it is possible to make scientifically meaningful probabilistic statements about future seismicity by treating every earthquake as a possible foreshock. However, whether, and if so, how much, such probabilistic forecasts are of use to society remains an open question. Workers in this area should be cautious in claiming possible benefits to society until these have been definitively established.
Foreshocks have the highest correlation with future seismicity of any physical phenomenon that has heretofore been observed. Furtheremore, although we do not yet understand the mechanism in full, there is a credible physical relation. In contrast, almost all other phenomena that have been claimed as precursors (e.g., electromagnetic signals) appear to have a much lower level of correlation, and there are strong suggestions that such signals could be artefacts due to human activity (e.g., radio-telecommunications transmitters) or other natural sources (e.g., lightning).

• Abstracts by Robert Geller