The Ansei Edo Earthquake as a Turning Point

According to prevailing wisdom at that time, the Ansei Edo earthquake should never have happened because water wells were common throughout the city. The possibility of a large earthquake was therefore beyond the imagination of Edo's residents, thus adding to its psychological impact. What about the Genroku earthquake of 1703? Why did that event not suggest to the people of 1855 that Edo was subject to large earthquakes?
Historical amnesia may have played a role, but the main factor was the history of Edo's water supply. In 1703, Edo's water supply was mainly a series of open pipes that brought water in from upstream areas of the major rivers. Three major networks—the Kanda system, the Tama system, and the Mita system—supplied water of adequate quality to all of the warrior housing areas and most commoner areas. Starting in the eighteenth century, however, many daimyō and other samurai began digging their own wells to obtain better and more convenient water. Gradually, commoner neighborhoods also began digging wells, and communal wells became the center of neighborhood micro communities.[1] This building of wells began just after the Genroku earthquake, so it was easy to explain that event as a buildup of yang energy within the earth but also to think that future large earthquakes were no longer possible.

Anyone who gave serious thought to the Ansei Edo earthquake's physical causes, therefore, would have had to question the theory of trapped yang energy. One reaction was to turn to Dutch books in search of better theories, or at least alternative ones. Moreover, as exemplified by designs for earthquake warning devices, scientific literature after Ansei Edo reflected optimism that ways of predicting or defending against earthquakes could be found. One particularly interesting example is Utagawa Kōsai's 1856 Earthquake Prevention Theory (Jishin yobōsetsu). Its main text was based on a recent translation of an article in a Dutch periodical, Nederlandsch magazijn. Earthquake Prevention Theory dismissed a variety of earthquake explanations such as cave-ins, underground explosions of combustible material, or the violent upwelling of steam or hydrogen gas. “There is but one source of earthquakes, and it is electrical [erekiteru] power. . . . Earthquakes come about because of electricity [denki] lying under the earth.” Just as electricity in clouds produces lightning, a similar process occurring under the earth produces an earthquake. The text concludes by arguing for the need to place the equivalent of lightning rods within the earth. Metal rods inserted deep into the earth would conduct electricity up, out, and into the air. Digging the deep holes for this purpose would be expensive, which is why no government or other entity had yet put it into practice.[2]

This electrical theory had a long history in Europe, and it fit in well with observed and imagined phenomena in Japan.[3] It was similar to the trapped yang theory but sufficiently different to explain the 1855 event. Moreover, it fit well with the idea of earthquakes as underground thunder and lightning and with the many reports of energy or light emanating from the ground during earthquakes. Electricity was very much in the intellectual air in 1856. Another work published that year, Yamazaki Bise's Thoughts on the Year of the Great Earthquake (Ōjishin rekinen kō), discusses earthquakes, thunder, and lightning at some length. It then provides what might be the earliest example of explicit instructions for constructing an earthquake-resistant building.

Because electricity was the force behind both earthquakes and lightning, the proposed design model would defend against both (fig. 5). A wooden pole in the center of the structure, sunk into the earth, wrapped in a stone base, and protruding well above the roof, would serve as the base for iron extensions attached to its top. Four large jars were sunk into the earth like wells, one on each side of the structure. An iron chain attached the top extensions of the central lightning rod to each well. The system would conduct electricity from storms or within the earth to the top of the lightning rod. Presumably, it would dissipate into the air or into the pole made of nonconducting materials.[4] There is no evidence that anyone attempted this construction technique, and it raises the question of how the dissipation of electricity on such a small scale could actually reduce ground motion. Nevertheless, its appearance at this time is an early manifestation of an active approach to mitigating earthquake hazards, even if utterly ineffective.

Two other translations of Dutch works on natural science contain explanations of earthquakes. Kawamoto Kōmin's Lectures on Natural Science (Kikaikanran kōgi) is a translation of Johannes Buijs' (1764–1838) Natuurkundig schoolboek. The translation took place between 1851 and 1857, with the explanation of earthquakes appearing in either 1856 or 1857.

It puts forth two theories. One is that hydrogen, when heated, combines with oxygen, undergoes combustion, and causes the earth's crust to move. The second is that saltpeter, charcoal, and sulfur are located in close proximity at the focus of an earthquake. Heated oxygen ignites this mixture, causing combustion, ground motion, and noise. Similarly, Hirose Genkyō's Essentials of Natural Science (Rigaku teiyō) is based on his reading of several Dutch books. His explanation of earthquakes relies on the basic idea of explosions within the earth causing ground motion. When this phenomenon manifests itself above the earth, it is in the form of volcanic activity. Below the earth, it becomes an earthquake. The basic mechanism is for saltpeter, charcoal, and sulfur within the earth to explode. There are three possible ignition sources: (1) rocks that emit fire; (2) hydrogen within the earth that mixes with oxygen in the atmosphere to create a combustible combination; and (3) rocks or soil from above that fall into holes and crevices in the earth, generating fire on impact.[5]

These new ideas were not highly influential, but their appearance in 1856 and 1857 indicates that the Ansei Edo earthquake encouraged a questioning of received knowledge in academic circles.[6] Indeed, a major significance of that earthquake is that it prompted a search for alternatives to the yin-yang theory of earthquakes. Moreover, the plans for earthquake prediction devices and earthquake-resistant building design indicate a new attitude toward earthquakes. The general idea was that careful observation

Figure 5 Perhaps the earliest example of earthquake-resistant building plans in Japan, from Thoughts on the Year of the Great Earthquake (Ojishin rekinen ko, 1856).

of seismic precursors and a better understanding of the mechanics of earthquakes could serve as the basis for earthquake prediction and engineering innovations to mitigate earthquake damage. In chapter 6, I explain that this notion helped transform the Ansei Edo earthquake from an event characterized by renewal in 1855 and 1856 into a menacing example of society's failure to heed the warning signs during the early Meiji period. More recently, events such as the Hanshin-Awaji (Kobe) earthquake of 1995 and of course the Great East Japan Earthquake of March 11, 2011, remind us that we still lack any practically useful warning signs to read, despite folk claims to the contrary. Although earthquake prediction in any useful sense remains elusive, earthquake-resistant building and infrastructure design has proven to be highly effective.

  • [1] Hatano, Jun, “Edo’s Water Supply,” in James L. McClain, John W. Merriman, and Ugawa Kaoru, eds., Edo and Paris: Urban Life and the State in the Early Modern Era (Ithaca, NY: Cornell University Press, 1994), 247–248.
  • [2] Udagawa Kōsai, Jishin yobōsetsu (Edo: Suhara Yaihachi, 1856). Quoted passage, 2; illustration of the rods, 16. See also Hashimoto, Jishingaku, 35–36.
  • [3] Experiments in electricity by Benjamin Franklin and others and the occurrence of several earthquakes in the middle of the eighteenth century prompted scientists such as William Stukeley to posit a connection between seismic activity and electricity in the atmosphere in 1750. A year later, Andrea Bina proposed disequilibria in underground electrical fluid as a cause of earthquakes. Writing in response to the Rimini (Italy) earthquake of 1786, Giuseppe Valadier proposed the construction of giant “para-earthquake” towers that served as lighting rods to channel dangerous electric vapors into the ocean. See Guidoboni and Ebel, Historical Seismology, 115, 173–180.
  • [4] Yamazaki Bisei, comp., Ōjishin rekinenn kō (1856), in Edo josei bunko. Sixth illustration after the table of contents.
  • [5] Hashimoto, Jishingaku, 36–38.
  • [6] Explosive theories of earthquakes had a long history in Europe. In Principia philosophiae (1644), for example, René Descartes advanced a theory of earthquakes whereby fumes from inside the earth might combine to form combustible mixtures. Soon after the Ansei Edo earthquake, Irish engineer Robert Mallet began important work on seismic waves. Mallet thought that explosive forces of volcanic origin caused earthquakes. See Guidoboni and Ebel, Historical Seismology, 167, 170–172, 184.
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