On Shaky Ground

by Nance, John J. ;

  4. Tsunami is a Japanese word meaning “great wave.” Normally, though, it is used only to describe massive waves in ocean areas which are caused by sudden movement of the ocean floor. Waves which occur inside a harbor or lake that resemble water sloshing back and forth in a tub are given a French name: seiche (pronounced “saysh”).

  By the way, contrary to popular belief, there are no such things as damaging “tidal” waves. With the exception of small tidal rips and waves created by tides flowing in or out in places of extreme tidal variations such as Puget Sound and the Bay of Fundy in Nova Scotia, tidal waves are a myth as amusing to scientists as mythical “air pockets” (which don’t exist) are to aviators.

  Chapter 8

  1. It was estimated that the seismograph needles at the Lamont-Doherty Geological Observatory at Columbia University in New York would have traveled an additional foot beyond their mechanical stops if not restrained. The reflection and refraction of the saturated wave trains coursing through the planet made interpretations of magnitude and epicenter very difficult in the first few hours, as well as during detailed analysis in the following months and years.

  2. In fact, Cordova was not wiped out. Some damage to buildings occurred, but very little physical damage to the city resulted from the ground shaking or the seismic sea waves which arrived later. The Cordova waterfront, however, was devastated economically by a simple and catastrophic gain in altitude. The tectonic uplift in the region thrust all of Cordova 6.5 feet higher than before in relation to sea level, rendering the commercial waterfront facilities unusable. All the dock structures were left too high to be reached at anything other than high tide, and the entire fishing industry was severely hurt. Cordova would recover, but it would take many years.

  3. It was the third and fourth waves which trapped and drowned some of the people at Crescent City when they made the fatal mistake of returning prematurely to their homes and businesses, thinking that tsunamis only come as one wave. To the south, in an amazing act of mass misunderstanding of the potential forces involved, some ten thousand Californians streamed down to the ocean beaches in San Francisco to watch the wave come in. In fact, this sort of tendency can be found in almost all natural disasters in the United States in which there is a stated threat but no visible sign. Even in hurricanes, such as Hurricane Camille in August 1969 at Gulfport, Mississippi (the most powerful hurricane to ever hit the United States, with winds above 235 knots), some of the 139 people lost were killed while having a blasé “hurricane party” in a beachfront motel. The tendency to “go down to the beach to watch incoming tsunamis” accounted for loss of life in Hilo, Hawaii, in the late forties, and could have resulted in massive deaths in many other locations.

  Chapter 9

  1. Not that the earth beneath New York City has never shaken. It has, with many small tremors from epicenters of unknown origin connected to little-understood faults. Faults run beneath the city as well as nearby. Cities as close as Buffalo, New York, are proven high-risk seismic zones, as is much of the St. Lawrence Seaway.

  2. Bryce Walker’s excellent book Earthquake (Time-Life, 1982) presents an entertaining rendition of the Boston quake which was a source for this paragraph. It maintains that Benjamin Franklin, “who had left his publishing business in 1748 to devote more time to science, had proved the existence of electricity in storms with his famous kite experiment. Soon after, he had invented the lightning rod and promoted its widespread use.” Since the popular “scientific explanation” for earthquakes in Boston in 1755 was that they were somehow related to static electricity, Franklin “believed that electricity had a role in causing earthquakes,” and the idea was accepted even by the formidable Reverend Thomas Prince, who had been preaching since the tremors of 1727 that such events were, as he titled a famous sermon, “The Works of God and Tokens of His Just Displeasure.” In a 1755 revision of the sermon, Prince suggested that God’s displeasure might be electrical in nature, and might be affected by the forest of Franklin’s lightning rods atop Boston’s roofs.

  The Lisbon disaster in the same year of 1755 was a watershed in European history and philosophy as well as in seismology. More than sixty thousand people died in the Portuguese capital, which had been the self-appointed bastion of Catholic piety and a stronghold of the Inquisition. It was the Age of Reason, and philosopher-writers such as Immanuel Kant and Jean Rousseau formed a school of optimists who argued that theirs was the “best of all possible worlds” in which everything that happened, happened for a beneficial reason. The Lisbon quake wounded the philosophy badly, and gave pragmatists such as French philosopher Voltaire the impetus to lampoon the optimists’ rosy philosophical ideas with his bitingly sarcastic novel Candide.

  3. Although the Richter magnitude scale is the one used principally by the media in reporting the relative sizes of earthquakes, there are other scales of similar logarithmic progression now in use which better describe the full range of power of major and great earthquakes outside the California area (which was Richter’s intended application area for the scale that bears his name). When an earthquake is described as being above 9.0, for instance, the scale being used is most likely called the moment magnitude scale. Although it works exactly the same as the original Richter scale in terms of showing each tenfold increase in ground amplitude as an increase of only 1.0 in magnitude, it takes into account a measure of the energy released as well as the size of the seismic waves produced. A straightforward explanation of all this may be found in Appendix 1 of this work, and for clarity and precision through the rest of the test, the magnitudes of different earthquakes will be presented with the designator for the scale used in accordance with Appendix 1. Therefore, you may see a reference to a Richter magnitude 5.6, or a Mm7.5 (for moment magnitude), or an Ms 6.6 (for surface magnitude). The scales are sufficiently similar, however, for you to disregard the subscript (“S” or “We” or “L”) and consider only the number. An MW9.5, for instance, is still approximately one hundred times as great as an ML7.5, or ten times as great as an MS8.5.

  Chapter 10

  1. Bradbury had a commission from the Botanical Society of Liverpool to study and collect specimens of North American plant life.

  2. The islands south of the confluence of the Ohio with the Mississippi were simply numbered in sequence downriver.

  3. The journals of John Bradbury can be found in several locales, along with at least one letter to a friend in New Orleans. Perhaps the most detailed glimpse is from a book entitled Voices on the River—the Story of the Mississippi Waterways by Walter Havinghurst (New York: Macmillan, 1964). The quoted material in these paragraphs are from this source.

  4. Elizabeth Bryan wrote these words in a letter to the evangelist Lorenzo Dow several years after the quakes (dated March 22, 1816). The letter has been quoted and reprinted many times, but the literacy of the lady, and the corroborating writings of so many other literate and well-educated people (such as botanist John Bradbury) who were in the area at the time, have given us a rare insight in substantial detail to a series of events which occurred, essentially, in the middle of nowhere. So detailed were the reports and the subsequent newspaper articles that 150 years later Dr. Otto Nuttli was able to draw up a detailed map and analysis of the intensity of ground shaking from the December 16 and February 7 shocks.

  Bryan (sometimes spelled Bryant) is a figure of some mystery. Author Harry Harrisson Kroll in his early historical novel Fury in the Earth: A Novel of the New Madrid Earthquakes assigned her the profession of schoolmarm. But as New Madrid earthquake scholar and authority Professor James Lal Penick, Jr., points out in his definitive work, The New Madrid Earthquakes (Columbia, Mo.: University of Missouri Press, 1981), “… while this additional information cannot be refuted absolutely, neither can it be confirmed.”

  5. One young settler who later became a colonel in the U.S. Cavalry, John Shaw, returned to the shattered remnants of the town amidst the constant aftershocks to help young Betsy Masters. With her leg broken be
low the knee, she was unable to move. Shaw cooked some food for her and tried to make her more comfortable before returning to the “grand encampment” with the others.

  6. Otto Nuttli originally estimated the three principal shocks at 7.2, 7.1, and 7.4 respectively in Mb values on the Richter scale but later revised those values upward. On the Modified Mercalli Intensity Scale, which is the principal measure of how intensely earthquake waves of any magnitude earthquake affect particular areas, the waves ranged from a high of XI at New Madrid on February 7, 1812, to values as high as V for Washington, D.C. Please see Appendix 1 for an explanation of the various magnitude scales and the Mercalli Intensity Scale.

  Chapter 11

  1. This Chilean quake would, in fact, be called the largest earthquake in recorded history.

  2. The World-Wide Standard Seismograph Network (WWSSN) is a network of approximately 110 seismograph stations similarly calibrated and distributed throughout the world. The network was originally established in the early 1960’s to help monitor Soviet nuclear tests by reading their seismic waves, and the USGS now coordinates its activities. Six seismometers at each station measure vertical and horizontal ground motion in two fixed frequency ranges, and transmit that information to the USGS center in Golden, Colorado, twenty-four hours a day.

  3. One model of the earth’s crustal structure at that time held that the Pacific basin was rotating slowly counterclockwise, and thus was ringed by steeply dipping (not necessarily vertical) faults which would periodically break at various points, causing slippage, some variations in coastal levels, and earthquakes up to the level of great quakes. The model considered the entire Pacific to be ringed by the very same type of strike-slip fault as the famed San Andreas in California. There were many flaws with that model, and in fact, the subsidence and emergence Plafker was documenting could not be explained even in gross terms by the theory. In addition, with what we now know about hot spots in the crust (a hot spot is basically a flume of intense thermal activity from deep within the planet which punches a hole through any crust that passes over it, causing volcanoes and, in the ocean, island-building activity), if the rotating-basin theory were true, the Hawaiian chain from Midway and the French Frigate Shoals through the big island of Hawaii would be arranged in a circle—an arc—instead of a relatively straight line, since the “turntable” of the Pacific floor would have rotated for millions of years over that same hot spot. In fact, the Hawaiian chain provides a graphic trace of the direction and extent of movement of the mid-Pacific Ocean for the last few hundred million years. By the same token, the historic path of the hot spot which now underlies Yellowstone National Park in Wyoming can be traced with great ease from the West Coast of the United States to its present position, forming the strange features of eastern Idaho all the way back to the Pacific coastline.

  4. The article was entitled “Science: The Earth’s Upheavals,” by Walter Sullivan on page 6E of the New York Times Sunday edition on July 11, 1965.

  5. Certainly with eminent scientists such as Press, such disagreements are minor career glitches and are handled in gentlemanly fashion.

  6. Wegener wrote: “The continents must have shifted. South America must have lain alongside Africa … the two parts must then have become increasingly separated over millions of years.” (Quotation selected by Samuel Matthews in his National Geographic article “This Changing Earth,” January 1973).

  “Utter, damned rot!” raged one scientist in 1920. The reaction, of course, was as old as science itself. One constant of human behavior is the tendency to institutionalize, then nearly deify, “established” conclusions or answers, and then to be outraged and threatened when at some later date or age someone comes along with a new way of viewing things and with the temerity to question the established order. From the outrage and indignation which greeted Aristotle’s ideas to the fury with which medieval religious leaders rejected any question of the church’s view of the cosmos, the definition of “heresy” has historically included any radically new scientific idea.

  The history of western civilization is full of incredible discredited “truths” which were once sacrosanct. (For instance, there must have been a radical change in the orbits of the sun and the planets in our solar system during the past several hundred years, since in the Middle Ages it was an unquestionable fact that they revolved around the earth—which itself was quite flat at the time.)

  The longer a theory goes without serious challenge, the more it tends to be regarded as the natural order of things—the ultimate answer—the final word.

  It is right and necessary that once a theory is established, a high standard of proof should be required to change scientists’ minds about how nature really works. Once erected like an alabaster citadel, the “established theory” on any scientific subject should enjoy a certain presumption of correctness. New ideas and theories should be forced to approach the gates of the citadel cautiously, lest their lack of preparedness or lack of proof leave them vulnerable to fatal attack by those who reside within the comfortable confines of the accepted theory.

  Time and time again the scientists of the day have clung tenaciously to an accepted “reality” whose foundation of legitimacy is being eroded with each succeeding scientific paper. The battles which develop between the warring men and women of science have often gone far beyond the bounds of careful skepticism and ended up holding back the advance of our scientific understanding.

  In the final analysis, of course, it is merely human nature at work: our human tendency to want to know what is true and once “known,” to cling to that belief, as well as our tendency to put protection of reputation above the greater good of scientific gain.

  Such was the treatment of Wegener and his prophetic (if ill-supported) theory. As his detractors pointed out, the idea that continents somehow plowed through the earth’s crust in constant motion, and that they all had once been a part of a single supercontinent in the dawn of geologic time, was based as much on artful leaps of his prophetic mind and imagination as on hard supporting evidence. While it was true that the geologic evidence for separation of Africa and South America was fairly substantial (plants and microorganisms from each side matched amazingly well), the “mechanism” Wegener proposed to explain the drift was unsupported by fact, and therein lay the controversy, and the conflict with the scientific method, which demanded a much closer connection between known facts and proposed theory.

  Nevertheless, it was basically right—a fact which would take earth scientists more than a half a century to discover.

  In the meantime, any graduate student who expressed a serious interest in the theory of continental drift could be sure of harpooning his career as certainly as if he opened his oral exam for a Ph.D. by expressing support for the “science” of alchemy or witchcraft.

  7. As molten rock cools and solidifies after a volcanic eruption, bits of ferrous metal in the rocks are left aligned magnetically with the earth’s magnetic field as it exists at that time. Many years ago geologists discovered that the earth’s magnetic field reverses at intervals over millions of years in rather regular cycles, and that drifting of the earth’s magnetic poles or periodic reversals can be dated because the changed orientation becomes locked in the magnetic alignment of volcanic rocks whose date of origin can be determined through carbon dating techniques.

  With the voyages of the research ship Vema in the Atlantic in the fifties, scientists began to notice that bands of the ocean floor running north-south all reflected one magnetic alignment, while an adjacent band (either the next one to the east or west) had the opposite magnetic alignment. Eventually it was discovered that as each of the bands were extruded as magma along the mid-Atlantic rise, the existing alignment of the earth’s magnetic field was “recorded” in the rocks as they cooled and hardened. The discovery became one of the keys to validating the constant extrusion of magma in the mid-Atlantic rift and its conveyorlike progress both east and west of the rift. The phenomenon was called mag
netic reversal.

  8. A zone of extension is an area of the ocean floor in which new magma is coming to the surface and creating new seafloor, which is constantly creeping away from the zone in both directions. The mid-Atlantic rise is a zone of extension.

  9. Benioff believed that the dipping, hypocentral zones marked major faults, but that movement was now horizontal (strike-slip) rather than dip-slip thrusting.

  Chapter 12

  1. Wallace’s insight ran to greater questions as well. It had occurred to him that since the fault slipped, it would be helpful to society and science to know the rate of slippage per year. That, he reasoned, might enable some calculations on how fast strain might be building in the fault. It was a small point in an already excellent paper, but it would prove to be the first time anyone had suggested looking into such a question.

  Bob Wallace has always professed to be embarrassed by his thesis, because it is not as extensive as the style and manner of such doctoral dissertations today. It was, he protests, “quick and dirty,” and limited by the war. Nevertheless, it has, by his own admission, stood up well enough with prophetic conclusions and postulations which turned out to be true.