Into the Twenty-First Century

As a general model of the effects of earthquakes over time, Jelle Zelinga de Boer and Donald Theodore Sanders propose the metaphor of a vibrating string: “If we think of an earthquake as the plucking of a long, tightstretched string representing time, the string will vibrate. During the quake itself . . . the vibrations will have high amplitudes and short wavelengths. They will be powerful, but each will last only a moment. Farther along on the string, with the passage of time, the amplitudes will decrease and the wavelengths increase. That is to say, the aftereffects will become less intense and they will last longer.”[1] The Ansei Edo earthquake conforms to this pattern. An example of a high-amplitude, short-wavelength effect was the redistribution of wealth so prominently discussed in prints and other popular media. Less than a year after the main shock, the influx of workers from outside Edo had substantially eliminated windfall profits. The political effects, including the strain on bakufu finances, were less obvious but longer lasting. This chapter examines the low-amplitude, long-wavelength side of the spectrum, exploring ways that the Ansei Edo earthquake has influenced modern and contemporary understandings of earthquakes in Japan.

The impact of the Ansei Edo earthquake lasted far beyond the fall of the bakufu. The event persisted in popular memory and as a reference point among Japan's pioneer earthquake scientists and architects. During the late nineteenth and early twentieth centuries, seismologists developed tools and techniques for measuring earthquake-related metrics, but they lacked an understanding of the geophysical mechanisms that cause earthquakes. An appreciation of the significance of faults developed early in the twentieth century, but the theory of plate tectonics did not become widely accepted in Japan until the 1970s. In Japan, one result of this gap between the capacities for measuring versus explaining was that lore from the Tokugawa period continued to influence modern seismological thinking and investigations. My basic argument in this chapter is that key elements of the Tokugawa past have conditioned modern and contemporary Japan in the realm of popular thought, in the development of seismology, and in perceptions of Japan and its relationship with earthquakes.

A comprehensive discussion of the history of seismology is beyond the scope of this study. However, because Western science and the accumulated body of Japanese earthquake observations and lore merged during the Meiji era, a brief consideration of understandings of earthquakes in the Western world provides useful context. Here I focus on pioneer geologist Charles Lyell (1797–1875), whose major work, Principles of Geology, was roughly contemporaneous with Thoughts on Earthquakes (Jishinkō) in Japan, both temporally and in the extent of its impact.

Writing in the middle of the seventeenth century, René Descartes posited water and water vapor as causing earthquakes, “when exhalations, collected and ignited in the earth's cavities, suddenly rarefied causing the earth to shake.”[2] By the time Lyell published vast, detailed information on past earthquakes from many parts of the world, the quantity of geological knowledge had grown enormously compared with Descartes' day. Earthquake causes, however, remained an enigma.

Lyell regarded the effects of earthquakes as instrumental in shaping the natural landscape, but he was unable to offer a convincing theory of their causes. One theory he entertained was that waves in the earth's molten interior caused earthquakes. He also considered electrochemical theories and the possibility that escaping gas, liquefied under pressure, produced the force necessary to shake the earth.[3] Discussing connections between earthquakes and volcanoes, Lyell proposed a mechanism similar to but more complex than the Japanese idea of yang trapped within the earth: “If earthquakes be derived from the expansion by heat of elastic fluids and melted rock, it is perfectly natural that they should terminate, either when a volcanic vent permits a portion of the pent up vapours or lava to escape, or when the earth has been so fissured that the vapour is condensed by its admission into cooler regions, or by its coming in contact with water. Or relief may be obtained when lava and gaseous fluids have, by distending the strata, made more room for themselves, so that the weight of the superincumbent mass is sufficient to repress them.”[4] Similarly, in the context of wavelike motions of the earth's surface during earthquakes, after likening strata in the earth to a large carpet or rug shaken up and down at one end to produce waves, Lyell explains, “In like manner, a large quantity of vapour may be conceived to raise the earth in a wave, as it passes along between the strata which it may easily separate in an horizontal direction, there being little or no cohesion between one stratum and another.”[5] Even though he understood earthquakes in a manner roughly similar to many of his contemporaries in Japan, Lyell's knowledge of the broader geophysical context, including the earth's strata, the potential roles of pressure, and wave mechanics exceeded the knowledge available in Japan. In hindsight, of course, it is easy to see what was missing: an understanding of faults and the forces that act on them.

As for faults, Lyell did use the term in discussing the dramatic sinking of the marble quay during the Lisbon earthquake of 1755: “In this case we must either suppose that a certain tract sank down into a subterranean hollow which would cause a 'fault' in the strata to the depth of six hundred feet, or we may infer, as some have done, from the entire disappearance of the substances engulphed, that a chasm opened and closed again.”[6] The basic definition of a fault is a discontinuity surface displaced by sheer forces. Lyell, therefore, happened upon a key element in modern earthquake theory, but he did not develop it systematically.

Most accounts regard the dramatic displacement along the San Andreas Fault after the San Francisco earthquake of 1906 as revealing the key link between faulting and earthquakes. The idea had earlier roots. For example, in 1883 G. K. Gilbert of the U.S. Geological Survey spoke of the earthquake hazard posed by Utah's Wasatch Fault.[7] In Japan, the Nōbi earthquake raised a prominent fault scarp (see fig. 1), which geologist Kotō Bunjirō publicized.[8] Tsuji Yoshinobu points out that one illustration in Foundation Stone (Kaname'ishi) clearly shows a ruptured fault line in connection with the Kanbun earthquake.[9]

Compared with Japan, the geological sciences advanced further in Europe, especially Britain, by the middle of the nineteenth century. Owing to its high levels of seismic activity and relatively long history of detailed record keeping, Japan could serve as a treasure trove of data. British seismologists, therefore, found Japan a fertile place to work. Italy functioned similarly, and many Western-oriented accounts of the history of seismology locate the beginnings of seismology there. According to Peter M. Shearer, for example, “In 1857 a large earthquake struck near Naples. Robert Mallet, an Irish engineer interested in earthquakes, traveled to Italy to study the destruction caused by the event. His work represented the first significant attempt at observational seismology and described the idea that earthquakes radiate seismic waves away from a focus point (now called a hypocenter) and that they can be located by projecting these waves backward to the source. Mallet's analysis was flawed since he assumed that earthquakes are explosive in origin and only generate compressional waves.”[10] Knowledge of the history of science in Japan could modify Shearer's assessment. For example, the general idea of seismic waves radiating from a focus point was already known in Japan. Moreover, owing in part to the influence of Dutch publications and in part to the Ansei Edo earthquake, explosive theories of earthquake origins had also become prominent in Japanese academic circles by 1857.

Shearer's account of the history of seismology mentions a few twentieth-century Japanese seismologists but says nothing about the origins of seismology in Japan. Nevertheless, it is possible to argue that modern seismology was as much an Anglo-Japanese science as anything else. The key development was the arrival in Japan of John Milne (1850–1913) to teach geology and mining in 1876. Milne sought to improve upon Mallet's “observational seismology,” which depended on sorting through and measuring wreckage patterns.[11] From the late 1870s, Japan became a major center for seismological research. One advantage Japan had over most other locations was its own seismicity and the vast historical data from the Tokugawa period. The detailed description of damage found in many earthquake accounts could, if well analyzed, serve as a variety of observational seismology. Initially, of course, Japanese scholars were the only ones in a position to find, compile, and analyze this massive data, a process that continues to this day and has informed this book.

  • [1] Jelle Zeilinga de Boer and Donald Theodore Sanders, Earthquakes in Human History: The Far-Reaching Effects of Seismic Disruptions (Princeton, NJ: Princeton University Press, 2005), x–xi.
  • [2] Rachel Laudan, From Mineralogy to Geology: The Foundations of a Science, 1650–1830 (Chicago: University of Chicago Press, 1987), 43.
  • [3] Laudan, Mineralogy to Geology, 218.
  • [4] Charles Lyell, Principles of Geology: Being an Attempt to Explain the Former Changes of the Earth’s Surface, by Reference to Causes Now in Operation, 2nd ed., vol. 1 (London: John Murray, 1832), 539–540. For the complete discussion of earthquakes, volcanoes, and related phenomena, see 457–553. For theories of earthquakes, see 533–545.
  • [5] Ibid., 543.
  • [6] Ibid., 505.
  • [7] Susan Elizabeth Hough, Earthshaking Science: What We Know (and Don’t Know) about Earthquakes (Princeton, NJ: Princeton University Press, 2002), 205.
  • [8] Kotô, Bundjiro [Kotō Bunjirō], “On the Cause of the Great Earthquake in Central Japan, 1891,” Tōkyō teikoku daigaku kiyō, rika 5, no. 10 (1893): 295–353.
  • [9] Tsuji Yoshinobu, Sennen shinsai: Kurikaesu jishin to tsunami no rekishi ni manabu (Daiyamondo sha, 2011), 252–253.
  • [10] Peter M. Shearer, Introduction to Seismology, 2nd ed. (New York: Cambridge University Press, 2009), 2.
  • [11] Gregory Clancey, Earthquake Nation: The Cultural Politics of Japanese Seismicity, 1868–1930 (Berkeley: University of California Press, 2006), esp. 63–66. See also Boumsoung Kim, Meiji, Taishō no Nihon no jishingaku: Rokaru saiensu o koete (Tōkyō daigaku shuppankai, 2007), 19–48.
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