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STEWARDSHIP: Environment & Energy | December 4, 1992


SEISMIC PATTERNS

An Unpublished Letter to Los Angeles Times

The following actually incorporates sound reasoning from some seismic theories that had previously been reported as having successfully predicted certain earthquakes or, in hindsight, might have predicted certain other earthquakes...

Although I am a biologist and not a geologist -- more at home among the lowly "bugs" than the mighty rocks -- I nonetheless feel compelled to submit a dissenting, well-reasoned earthquake prediction for the record.

Like the current official forecast, I, too, have been telling others that the "Big One" on the San Andreas Fault will probably occur near San Bernardino -- about halfway between the current crop of quakes near Landers/Big Bear and the other significant quakes in recent years, in and around Whittier, Upland, and Sierra Madre.

However, given the flurry of unusual seismic activity around Barstow, as reported in the Times, and the significant quake near Mojave shortly after the Landers/Big Bear quakes, I have revised my estimate: Using the faults northwest from Landers/Big Bear through Barstow as one side of a triangle; the intersecting fault southwest through Mojave as another; and the San Andreas Fault as the third side, I expect the "Big One" to occur near Wrightwood (significantly closer to the L.A. Basin than the officially predicted "ground zero") -- a historically seismically active area at approximately the midpoint of this "leg" of the San Andreas Fault.

The series of large quakes in recent years all seem to radiate from this central point; and according to reports in the Times, such a concentric pattern is the most reliable predictor, as preceded the devastating Coalinga quake. One would expect the magnitude to exceed that of the precursor quakes (7.5 maximum, at Landers); and the high likelihood of occurrence within the next 5 years according to the official prediction seems reasonable, given recent events. We have been warned!

Of course, I may just have rocks in my head. After all, I was the guy who wrote in almost ten years ago -- before our record drought of 7 years and counting -- to warn that the Greenhouse Effect (not a chic topic back then) might be affecting our climate. God only knows. Back to the "bugs"!

A little over a year later, the large Northridge quake hit. Although it was not "The Big One", it further refined my prediction: The ground-shaking effects of large quakes, including that in Northridge, often spread out asymmetrically, in a four-lobed pattern, which some seismologists nickname "the butterfly" (That concentric pattern mentioned above is sometimes called "The Moghi Donut", after the Japanese seismologist who first described it); and subsequent large quakes are often epicentered within one or another of the four "wings of the butterfly" -- indeed, Northridge was in one of the "wings" from the Sylmar quake, about 20 years earlier. Applying that pattern for predictive effect, one of the four "wings" of the Northridge "butterfly" intersected the San Andreas Fault in or around the town of Pear Blossom, a bit west of Wrightwood -- my refined prediction for the epicenter of "The Big One"...sometime in the near future (although in geologic time, that may well be decades, even though we're "overdue" for such an event). I don't panic, but I do check and refresh my emergency supplies annually and encourage others to do likewise.

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