Earthquake Precursors or Background Noise?

Claims made in the article "Earthquake Alarm," by Tom Bleier and Friedemann Freund [December] that electromagnetic (EM) observations are earthquake predictors should be rejected.

Earthquake prediction has been the subject of research for over 100 years, with no generally accepted success, although from time to time there have been spectacular claims of success that were later shown to have been artifacts¹. Earthquakes are the result of complex nonlinear failure phenomena, and there are strong reasons for pessimism² on prediction. The clear consensus of a 1999 Debate on Nature's Web site was that reliable and accurate prediction of earthquakes was not possible at present, although opinions were divided about the extent to which such research was worth pursuing in the future³.

Against this background of lack of progress, for many years there has been a small group of "believers" in the ability to predict earthquakes from EM signals. For example, P. Varotsos of the University of Athens and his co-workers (known as the "VAN" group) made such claims starting in about 1980. These claims eventually attracted enough attention that a special issue of Geophysical Research Letters (27 May 1996) was devoted solely to a "Debate on VAN." Although Varotsos and his colleagues and a few supporters did not agree, the consensus was that the correlation between VAN's signals and earthquake occurrence was not in excess of random chance. More recently, V.N. Pham and co-workers^4,5 showed that geoelectrical signals observed by VAN were of artificial, not natural, origin. As a result, interest in VAN has faded. Claims to have observed EM precursors of the 1989 Loma Prieta, Calif., earthquake⁶ are widely cited, but the signals in question have been shown to have been artifacts of solar-terrestrial origin, with no relation to the earthquake⁷.

The scientific problem afflicting all claims of EM precursors of earthquakes is that natural EM signals in the solid earth and atmosphere (due to solar activity, lightning, etc.) are ubiquitous, as are signals due to human activity (industrial facilities, electric-power generation, military and civilian radio and radar transmission, etc.). Before arguing, after an earthquake, that an EM signal that occurred before it was an earthquake precursor, the proponent must eliminate known artificial and natural causes other than earthquakes, and also demonstrate a statistical correlation exceeding random chance. Unfortunately, the proponents of work in this area have consistently failed to carry out such verification exercises. The result has been a steady stream of low-quality papers, primarily in low-quality forums, that fall "under the radar." Carefully vetting these claims is hard work, but, as in the case of VAN or Loma Prieta, when the claims have attracted enough attention to justify independent evaluation, they have been refuted.

One might argue that the rejection of VAN's claims, for example, does not justify rejection of Bleier's claims. But in our opinion that view is wrong unless Bleier can demonstrate that his work is free of the flaws that bedeviled VAN, which he has not done. The burden of proof, as in all science, is on the proponents, not the critics. And incredible claims call for incredibly strong data and theory, which Bleier and Freund fail to provide.

The editor of Spectrum may give the authors a chance to respond to our letter. Since debate on this topic is longstanding, we present and refute the type of arguments likely to be made.

1. Many international workshops on prediction of quakes using EM signals have been held, and hundreds of papers have been presented. It is surely unlikely that all of these papers are wrong, and a handful of critics are right. Reply: There have been many instances of threshold signals being incorrectly claimed as new physical effects. Cold fusion and polywater are among them. I. Langmuir collected many earlier episodes of this type, which he called "pathological science⁸." In each of these instances there were hundreds or sometimes thousands of papers on "phenomena" that ultimately proved to be nonexistent. The quality of the data and physical arguments, not the number of papers or meetings, is what is of paramount importance.

2. This is a new field of study that is slowly developing instruments and methods to prove (or disprove) the connection between earthquakes and EM signals. Reply: Since work in this field (VAN, for example) has been going on for over 25 years, it isn't "new" anymore. Further, the idea of "proving or disproving" a connection between earthquakes and EM signals is fundamentally flawed. Occam's razor tells us not to use complex hypotheses until simpler ones have been conclusively ruled out. Unless and until the null hypothesis (that the EM signals are due to known artificial and natural causes) can be conclusively excluded, the hypothesis that the EM signals are due to earthquakes need not be considered.

3. We don't yet have enough data to apply statistical methods. We need more time. Reply: A general principle of science is that empirical correlations cannot be accepted without convincing statistical evidence. Claims of EM precursors of earthquakes are not an exception. Work in this field has now been going on for over 25 years, and the absence of strong supporting statistical evidence does not bode well.

4. Weather prediction is a difficult problem, but progress is being made. Earthquake prediction is the same. Reply: Except for their use of the word "prediction," the two are completely different. Weather prediction is based on sound physics—the Navier-Stokes equation, and numerical extrapolation of observed data. In contrast, the efforts advocated by Bleier and Freund are purely empirical, with no quantitatively testable theory to back them up.

In summary, their claims should not be accepted.

[signed] Robert J. Geller, Alex I. Braginski, and Wallace H. Campbell

References:

[1] Geller, R.J., "Earthquake prediction: a critical review," Geophysical Journal International, 131, 425-450, 1997.

[2] Geller, R.J., Jackson, D.D., Kagan, Y.Y., Mulargia, F., "Earthquakes cannot be predicted," Science, 275, 1616-1617, 1997.

[3] Nature Debates: "Is the reliable prediction of individual earthquakes a realistic scientific goal?" http://www.nature.com/nature/debates/earthquake/equake_frameset.html

[4] Pham, V.N., Boyer, D., Le Mouel, J.L., Chouliaras, G., Stavrakakis, G.N., "Electromagnetic signals generated in the solid Earth by digital transmission of radio-waves as a plausible source for some so-called 'seismic electric signals,'" Physics of the Earth and Planetary Interiors, 114, 141-163, 1999.

[5] Pham, V.N., Boyer, D., Chouliaras, G., Savvaidis, A., Stavrakakis, G., Le Mouel, J.J., "Sources of anomalous transient electric signals (ATES) in the ULF band in the Lamia region (central Greece): electrochemical mechanisms for their generation," Physics of the Earth and Planetary Interiors, 130, 209-233, 2002.

[6] Fraser-Smith, A.C., Bernardi, A., McGill, P.R., Ladd, M.E., Helliwell, R.A., Villard, O.G. Jr., "Low-frequency magnetic field measurements near the epicenter of the Ms 7.1 Loma Prieta earthquake," Geophysical Research Letters, 17, 1465-1468, 1990.

[7] Campbell, W.H., "Natural magnetic fields preceding the Loma Prieta earthquake that damaged San Francisco in October 1989," Eos Trans. AGU, 86(18), Jt. Assem. Suppl., Abstract GP23A-01, 2005.

[8] Langmuir, I., "Pathological science," Physics Today, 42(10), 36-48, October 1989.

Geller is a researcher in seismology at the University of Tokyo. IEEE Senior Member Braginski is active in SQUID magnetometer research and applications. Campbell is a researcher in geomagnetism.

Robert J. Geller

Department of Earth and Planetary Science

Graduate School of Science

University of Tokyo

Tokyo 113-0033, Japan

Alex I. Braginski

ISG-2, Research Center Jülich

D-52425 Jülich, Germany

Wallace H. Campbell

3030 Galena Way

Boulder, Colo. 80305

(NOAA Solar-Terrestrial Physics Division, retired)

With Respect to Earthquakes

The 2005 International Workshop on Seismo-Electromagnetics, held from the 15th through the 17th of March in Chofu, Japan, was the fourth in a series of conferences held on this topic. Participants at Chofu published over 150 papers, many by respected scientists from over 20 countries. These papers include real data showing connections between earthquakes, magnetic fields, infrared emissions, and ionospheric perturbations that caused detectable radio-wave propagation changes.

It is hard to believe that over a thousand scientists involved with this work are all wrong and that [Robert J.] Geller et al., in their response to "Earthquake Alarm," by myself and Friedemann Freund [December], in which they reject our claim that electromagnetic (EM) observations are earthquake predictors, are absolutely correct. [See the complete text of the Geller letter above.] Rather, I think it is more accurate to say that this is a new field of study that is slowly developing instruments (ground- and satellite-based), as well as new signal-processing techniques to prove (or disprove) the earthquake-EM connection. I strongly believe that this ad hoc group is honestly looking for the physical source mechanism so that we can tune our instruments to reliably detect these short-term earthquake precursor signals.

Are we there yet? No.

Are we detecting very interesting signals? Yes.

Are we applying statistical methods? Yes, but not with enough data yet.

Can we make accurate short-term predictions yet? No, but there are definitely unique signals that appear to be different from normal man-made and solar-induced EM noise.

The present earthquake forecasting state is similar to the short-term weather-prediction problem that in the last 30 years began relying on more sophisticated ground- and space-based instruments, along with more sophisticated algorithms. The weather problem is very complex, but definite progress has been made.

Earthquake forecasting is also a complex problem, but there is too much data to suggest that we should quit just because we have not found one clear, irrefutable signal that works every time. It will probably require monitoring multiple EM signals simultaneously, and it will use more sophisticated algorithms to refine the process—and I suspect it will not work every time.

Luckily, there are many dedicated people out there who are willing to commit their careers to see this through.

Tom Bleier

Palo Alto, Calif.

Bleier is chief executive officer of QuakeFinder LLC in Palo Alto.