On Shaky Ground

by Nance, John J. ;

  2. Dr. Charles Richter was actually one of the best observational seismologists around, and, indeed, was first to report many “paleoseismological” and geological observations in his 1958 book Elementary Seismology, a work that still serves as the basic bible of beginning seismology courses worldwide.

  3. Gilbert’s comprehensive reports on the great earthquake which damaged San Francisco so badly in 1906 were reported formally by G. K. Gilbert and others in 1907, “The San Francisco Earthquake and Fire of April 18, 1906, and Their Effects on the Structures and Structural Materials,” U.S. Geological Survey Bulletin, no. 324 (1907), pp. 1–170.

  4. The quote comes from an excellent paper written by Dr. Robert Wallace in 1980 for the centennial celebration of the USGS (Geological Society of America Special Paper 183) on Gilbert’s contributions, in which he chronicled the almost precognitive ability Gilbert showed to construct theoretical models and theories that are still, in large degree, valid:

  “… Gilbert’s observation of small, fresh scarplets at the base of fault-generate range fronts indicated to him that:

  “‘A mountain is not thrown up all at once by a great convulsive effort, but rises little by little. When an earthquake occurs, a part of the foot-slope goes up with the mountain, and another part goes down (relatively) with the valley. It is thus divided, and a little cliff marks the line of division. This little cliff is, in geologic parlance, a “fault scarp,” and the earth fracture which has permitted the mountain to be uplifted is a “fault” (“A Theory of the Earthquakes of the Great Basin, with a Practical Application” [from the Salt Lake Tribune of Sept. 30, 1883]: American Journal of Science, 3rd series, Vol. 27, pp. 49–51).’

  “In a popular article in the Salt Lake Tribune, Gilbert carried the readers through the sequence of logic that:

  “‘(1) mountains of the Great Basin are uplifted along faults, (2) mountains “rise little by little,” (3) alternate cohesion and sliding characterizes the motion, and (4) the instant of yielding is so swift and so abruptly terminated as to constitute a shock’ [1884, p. 50].

  “This line of reasoning is so modern that, in 1980, it is difficult to understand why, once stated, the concept would not have been generally accepted and become a firm part of the working base of geologists and seismologists.

  “In the nineteenth century, however, the sciences of geology and seismology were unprepared to acknowledge the verity of several major facts that formed the foundation for Gilbert’s hypothesis.

  “Seismologists were preoccupied with the shaking phenomena, not with field observations.…”

  5. The report was entitled: “Earthquake Prediction: A Proposal for a Ten Year Program of Research,” Ad Hoc Panel on Earthquake Prediction, prepared for the Office of Science and Technology (May 1965).

  6. The engineering report—“Earthquake Engineering Research,” National Academy of Engineering—was not formally issued until 1969, though rumbles of its preparation and the upset which was driving its formulation were certainly no secret in Washington or in the seismological community in the years between Dr. Press’s effort and its issuance.

  7. The USGS-driven effort was entitled “Proposal for a Ten Year National Earthquake Hazards Program: A Partnership of Science and the Community,” Ad Hoc Interagency Working Group for Earthquake Research, Federal Council for Science and Technology (December 1968).

  8. The challenge facing Steinbrugge and his copanelists was formidable. There were intense seismological interests in basic research (and the funding to fuel it); geology’s increasing role and need for funding as a dynamic supporting actor on the stage of advanced earthquake research, prediction, and threat assessment efforts; the concerns of social scientists over what earthquake predictions could do to the society at any given point, and how the problems could be turned into advantages; and, the serious concern of engineers that those advances in engineering research and heightened standards for earthquake-resistant building design already realized, and those that could be realized, not be lost in a flurry of “misplaced” excitement over prediction. In addition, they had to deal with (and incorporate) the sensitivity of political leaders and economists who saw prediction attempts and large-scale hazard mitigation programs of changed building codes and standards as a loose economic and political cannon on a rolling national deck. And that, in turn, raised an issue which was squarely in the professional center of Karl Steinbrugge’s expertise: the ability of society to spread the financial risk of major natural disasters such as earthquakes through the operation of private enterprise: the insurance industry. Earthquake insurance existed, but the concept and the future of the nation’s involvement as a whole were not even embryonic in 1969 (though they would grow to form a major legislative challenge for the nation twenty years later).

  9. This quote is from the introduction page of: “Report of the Task Force on Earthquake Hazard Reduction, Executive Office of the President, Office of Science and Technology,” (September 1970).

  Chapter 13

  1. Dr. Charles Richter was a world-class scientist. Along with Dr. Beno Gutenberg, Richter had invented the unified magnitude scale (used for a particular wavelength of seismic energy) which permitted at long last a comparison of apples and oranges—different earthquakes at different depths the waves of which were read on different seismographs in different parts of the world. With the Richter scale, they all could be compared as apples to apples, giving at least an initial indication of size (please see Appendix 1 for a comparison of the different types of magnitude waves). Richter, who had received his doctorate from Caltech in 1928, never failed to give the lion’s share of credit to Gutenberg. But the world had already made its decision on how to refer to the method and the scale, making the name Richter and the phrase “Richter scale” extremely familiar to millions. And in the fifties Professor Richter had published the bible of modern seismology, titled simply Elementary Seismology, which became required reading for any serious student.

  Charles F. Richter, professor emeritus of Caltech, had retired eight months before (in June 1970), but even at the age of seventy he was still fully engaged and active, going to Caltech almost every day, serving as a consultant on many advisory committees and boards, and monitoring endlessly the seismograms that his efforts had helped so much to standardize and improve.

  “He’s supposed to be retired,” Mrs. Lillian Richter told a New York Times reporter, “… but mostly it’s just his salary that’s retired.”

  2. The elastic rebound theory was first developed by Harry Fielding Reid following his extensive study of the 1906 San Francisco earthquake and the effects of fault slippage on Marin County to the north.

  3. The San Gabriel Mountains, which form the northern flank of the San Fernando Valley and run eastward as the bordering line of ridges and mountains north of Los Angeles and San Bernardino, sit just south of the San Andreas Fault, and have been moving northwestward relentlessly for thousands of years with the western side of the fault. The mountains themselves are an upthrust core of Precambrian metamorphic and Mesozoic plutonic rocks flanked by thick sections of sedimentary strata.

  4. A comprehensive (and highly technical) examination of the seismographic tracings and the interpretation of the results which validated the accelerations greater than 1 G are contained in the professional paper, “Stress Estimates for the San Fernando, California, Earthquake of February 9, 1971 …,” by M. D. Trifunac, as published in the Bulletin of the Seismological Society of America, Vol. 62, No. 3, pp. 721–750, June, 1972.

  5. The faults which caused the quake were quite complex, it turned out, but had no direct connection to the San Andreas to the north, and, in fact, ran more or less at right angles to the San Andreas. There was some confusion at first over whether the slippage in San Fernando’s faults had increased or decreased the pressure on the San Andreas, or had had no effect at all. There is a technical but readable article on the preliminary conclusions regarding this subject written by D. F. Palmer and T. L. Henyey and
published in the May 14, 1971, issue of Science magazine.

  6. As Professor Richter pointed out to newsmen in the following days, there is no such thing as an “earthquake-proof” building. Nor is there ever likely to be such a thing. Earthquake-resistant, certainly. But not earthquake-proof.

  7. The Field Act did change the construction of new schools, and caused the abandonment of damaged, unsafe structures, but it took other laws in later years to force abandonment of marginal school buildings. Even then, this affected only public schools. Many of the buildings abandoned by the school districts as a result of the new laws were sold to private or parochial school systems, and remained in use, a few to the present day—all of them as dangerous and as potentially lethal as ever.

  8. In a February 12th article printed three thousand miles away in The New York Times (“Threat of Flooding Eases in California; 57 Now Dead in Quake,” Section 1, p. 16), Curt Gentry, an author who had written a popular novel about the supposed slide of the western side of the San Andreas—and much of the state—into the Pacific Ocean (an impossibility), complained bitterly to reporter Steven Roberts that “We’ve played ostrich in California with the earthquake hazard for too long.” It was ironic that Gentry’s novel had inadvertently retarded popular understanding of the level of threat from the San Andreas, but following its publication, seismologists’ efforts to refute the idea were often misinterpreted by the public as assurances that the fault could never cause widespread destruction. The truth, of course, was that California is destined to shake violently, not to split in half and sink. (Even the popular movie of the late seventies Superman I, repeated that same geologically improbable theme in the nefarious plot of archcriminal Lex Luthor. He didn’t succeed, by the way.)

  9. Once again, Dr. Karl Steinbrugge became involved, joining a score of other eminent scientists on a panel formed by the National Research Council to do a rapid evaluation of the lessons of San Fernando. Dr. Clarence Allen chaired the group, which published “The San Fernando Earthquake of February 9, 1971—Lessons from a Moderate Earthquake on the Fringe of a Densely Populated Region” two months later in April. The panel knew well the short memory of people and their government leaders. They knew that recommendations and ideas needed to be in front of a wide variety of officials asking for action on earthquake hazard mitigation, and that any such report would need to be issued rapidly.

  10. This is from the News and Comment article “San Fernando Earthquake Study: NRC Panel Sees Premonitory Lessons,” Science Magazine, Vol. 172, page 140–143, (April 9, 1971).

  Chapter 14

  1. A “sandblow” is an ejection of sand and water in a pressurized stream which punches through upper layers, usually all the way to and above the surface. Sandblows are caused by moderate to severe earthquakes, and occur when a layer of water-saturated subsoil takes on the characteristics of a liquid upon being shaken and compressed. The pressure drives the waterlogged sand and silt up through a fissure (or opens a path through homogeneous layers of soil above), leaving in many cases a mound of sediment on the surface that geologists can use to identify and later date the causative earthquake.

  2. Caltech, in fact, has to some extent institutionalized an atmosphere of controlled pranks and creative jokesterism on campus as a means of breaking the tension of intense academic competition at what has become one of the world’s best universities for the sciences.

  3. Jahns was considered a true genius by most who knew him. Indefatigable, ambidextrous, and charming, he had begun his career at Caltech by switching during his senior year from chemistry to geology and doubling up on his courses while serving as captain of the basketball and baseball teams and president of the student body, all the while maintaining a straight A average. According to Bob Wallace, Jahns once came into their dorm room at 1:00 A.M., sat down to do a term paper on a highly technical subject, and finished it two hours later at 3 A.M. When Wallace looked it over, the paper was perfect on the first draft. “It was,” said

  Chapter 15

  1. In fact a type of poison later banned by the federal government had been used in the area. 1080, as it was called, was used to increase crop yields, but it killed several times over. Any animal that ate prey which had died or consumed the poison, was itself killed, and that meant the effective eradication of all animal life in an area. Kerry Sieh discovered these facts months later.

  2. The Carrizo Plain is a desolate piece of landscape, but it contains the most photographed segment of the fault. Located roughly forty miles west of Bakersfield, geologists have recognized for decades the stark clarity of the San Andreas’ path as it cuts from north-northwest to south-southeast across the landscape like a giant zipper (as seen from the air)—wrinkled foothills and offset streams bisected by the fault scarp itself. The theory of plate tectonics had shown that all the land to the west sat on the Pacific plate, and that the western California edge of that plate was moving northwestward at an average rate that had been measured by marine geologists out on the ocean floor at 5.5 centimeters per year, but was later found to be 3.4 centimeters per year. To the east of the San Andreas Fault, the entire continental United States (and the floor of the Atlantic Ocean eastward all the way to the mid-Atlantic rise) sits on the North American plate. The dividing line—the seam—is the San Andreas Fault itself, which runs between the two crustal plates almost the length of California, producing earthquakes whenever the two sides of the fault suddenly slip past each other.

  3. A 1955 paper written by a Caltech seismological laboratory professor, Dr. Harry Wood, had already examined the historical accounts of the 1857 Fort Tejon quake, providing a wealth of human history on the event. But there were no seismograms available, or standard instruments in operation to record the waves anywhere near California at the time, so the usefulness of the reports was limited to measurements of the intensity of ground shaking.

  4. There was a reason for dividing the project into three semiindependent projects. If any one of the questions proved unanswerable, he could still finish his thesis—and his doctorate—with the remaining two.

  5. It was the basic strain-release cycle at work. Somewhere beneath the surface, perhaps forty to fifty miles below, the rocks are hot enough and plastic enough so that the two great plates could almost ooze past each other at a steady rate without causing earthquakes. However, the cooler crust at the top (the land that is California on either side of the fault), cannot slip at a steady rate (except, apparently, in the San Juan Bautista area). Snags develop between the upper levels of the two plates, locking them together at the top while at great depths they continue to slip past each other. That puts increasing pressure on the snags holding the top sections together, until at last a breaking point is reached. Then, if the bottom sections (many tens of miles beneath) have oozed past each other as much as 3.5 meters (for instance) in a hundred years while the surface level never slipped at all, when the breaking point comes, the upper surface level will snap back into equilibrium, and the west side of the San Andreas will suddenly slip up to 3.5 meters to the northwest, releasing enormous amounts of stored energy in the form of seismic waves.

  6. Free-lance surveyors were a common feature of the expanding frontier, and in fact, a majority of the older surveys in the West were done by such people under contracts of one sort or another to the government. Hancock and his son later acquired title to most of Rancho La Brea—the site of the famous La Brea tar pits, which now sit in downtown Los Angeles.

  7. Since the 1857 quake apparently resulted in movement of the fault through the Carrizo Plain and the Fort Tejon segments—and may have been triggered by the Parkfield segment to begin with—it is reasonable to assume that all three segments were fully strained and ready to break at the same time (although the Carrizo might have been somewhat short of the full amount of slip-deficit strain which would have been needed to cause it to break in the absence of a pulse from the Parkfield section to the north). Like the second, minute, and hour hands of a clock all coming togethe
r twice every day at the 12, the segment of the fault with the longest period—the Carrizo Plain—may occasionally be sufficiently “ripe” for a break at the same time the Fort Tejon segment to the south also comes into readiness for a break. When such a conjunction occurs, an initial pulse on the Parkfield segment (which itself is probably triggered by a small preliminary lurch in the so-called preparation zone north of Parkfield) may trigger the Carrizo Plain, which in turn triggers the Fort Tejon segment, creating a massive and monstrous release of pent-up seismic strain over a distance of several hundred miles, and causing a great quake in excess of 8.0 magnitude.

  8. When Bob Wallace first used the term in a professional article, one of his colleagues complained: “Oh, no! Please don’t clutter up the literature with still another term!” But Wallace was well aware that to rally fellow scientists around a new concept, it needed a name—a catalyst—without which a coherent momentum would not develop. It would be ten years, however, before the term gained official acceptance. By 1987 a new science called “paleoseismology” had emerged, and a major scientific conference had been held to validate the new discipline—a conference at which Bob Wallace gave the keynote address.

  Chapter 16

  1. For instance, on January 23, 1556, during the Ming dynasty, a great earthquake slammed into the city of Xiau in the Shoanxi Province, killing 830,000 Chinese (according to dynasty records).

  2. The extensive apocryphal reports of strange animal behavior just before earthquakes have fascinated and frustrated seismologists and other scientists for decades. Dogs, cats, horses, cows, other barnyard animals and fowl, fish, and even insects at various times and places have been reported to have acted in some unusual manner hours or minutes before earthquake waves arrived beneath them. While the tendency was to regard such stories as folklore, many serious scientific studies have tried to find valid links and explanations. Even in 1988 the best state of scientific knowledge is that animals and insects at various times and places seem to have the capability of sensing something, but what those advance warnings are, we do not know. In some circumstances they may simply detect changes in the earth’s magnetic or electrical field; in others, they may sense preliminary small earthquakes which humans can’t feel. But serious and careful attempts to monitor animals (and even cockroaches in one experiment) as an early-warning system have not provided scientists with any reliable or consistent ability to detect earthquakes before they occur. While the rural Chinese watch their animals carefully as part of their earthquake prediction and monitoring effort, reports of odd animal behavior simply reinforce other indicators (such as well water level changes and radon gas emissions) rather than provide a primary indicator in and of themselves. “There is definitely something going on,” according to one researcher, “but we’re still groping in the dark for what it is, and how it works.”