California needs to take earthquake prediction more seriously 

Helen Keller said the heresy of one age is the orthodoxy of the next, showing that while she was sightless, she possessed extraordinary vision. California might profit from such imagination, especially when confronting one of the state's foremost perils: earthquakes.

China, Japan and other nations have long since established agencies dedicated to seismic forecasting. The United States, though, is bringing up the rear. It's still very common to hear scientists and other authorities making pronouncements about the "impossibility" of a subject that should be front and center in California.

One particular dynamic should garner attention on the West Coast: conjoined lunar and solar gravitational tides. Gravitational tides are one of the overarching forces of the cosmos. Some of the solar system's most iconic features are shaped by them: the towering and ferocious volcanoes of Jupiter's moon Io and the hyper-geysers of Saturn's moon Enceladus. These are powers sufficient to nudge fault lines into action, especially those already under stress.

The currently accepted scientific view is that while tidal influence is an ancillary force in seismic activity, it is a minimal stimulus for producing earthquakes powerful enough to cause damage, inflict injuries and produce fatalities. Yet the historical record in Southern California provides empirical evidence that this opinion may underestimate conjoined lunar and solar gravitational effects.

Between 1933, the year of the Long Beach earthquake, and 1994, the year of the Northridge quake, six temblors large enough to cause fatalities struck within 70 miles of downtown Los Angeles. Each of those magnitude-5.8 to magnitude-7.3 quakes occurred either at dawn or at dusk. Every individual who perished in an earthquake during those 61 years in Greater Los Angeles died between the hours of 4-7:45 a.m. or 4-7:45 p.m. The probability of this happening randomly are in the realm of 1 in 5,000.

Not only did all these quakes strike either at dawn or dusk, but two-thirds of them also occurred within 36 hours of the new- or full-moon phase, when the gravitational pull of the moon and sun are combined. Such a remarkable occurrence due to simple chance is highly unlikely: 1 out of 10,000.

Here, then, is a possible first step toward a simple seismic advisory for California: dawn and dusk during certain new- and full-moon phases might hold a higher probability for seismic activity on the West Coast.

Bay Area residents would be the last to ask if this should be constrained to Los Angeles. As everyone knows, San Francisco's two great telluric disasters occurred almost exactly 12 hours apart: the first at 5:18 a.m. in 1906, the second 83 years later at 5:04 p.m. in 1989. The same hallmarks can be seen from San Diego to Vancouver, British Columbia, and beyond. The greatest earthquake in the history of North America, a magnitude-9.2 temblor, devastated Anchorage, Alaska, at dusk at 5:36 p.m., 47 minutes from the precise instant the moon entered the exact moment of its fullest extent.

A thorough investigation by an independent panel of experts should be undertaken to determine the viability or fallibility of a rudimentary seismic advisory based on the data outlined above. Such a panel actually exists: the California Earthquake Prediction Evaluation Council. San Franciscans who wish to voice their opinion on this matter are urged to contact Gov. Jerry Brown via a link to his offices at

David Nabhan is the author of "Earthquake Prediction: Answers in Plain Sight" and two other books on the subject.

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David Nabhan

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