Why the Earth Shakes

Late in 1662, Asai Ryōi wrote Foundation Stone (Kaname'ishi), a work of fiction in the guise of a journalistic account of the Kanbun earthquake. In an effort to conclude on an uplifting note, Ryōi explained that according to a poem by the Song Chinese intellectual Su Dongpo, the month in which an earthquake occurs determines fortunate or unfortunate events in the near future:

The prosperity of the people declines, the spring is “fire” [= the fire or hearth deity]; severe droughts occur

The second, fifth, and eighth months are “dragon” [= the dragon deity]; people of high status and low all perish

The sixth, ninth, and first months are “gold” [= the golden-winged bird]; the harvest of rice and other grains is abundant

The seventh and twelfth months are “emperor” [= celestial king]; wars and rebellions will occur.

Therefore, this year's earthquake signals an abundant harvest of the five grains and prosperity.^[1] Even the great sage kings of ancient times, whether in China or our country, could not avoid occasional disasters owing to the workings in yin, yang, and the five phases. It is only natural that such occurrences could happen today and should not be cause for alarm. On the contrary, at present, with the seas in all directions calm and society well governed, events like the present earthquake can be regarded as reports from the deities revealing the future, not as unfortunate happenings.

In popular lore, there is the notion that the world is supported by a dragon king, whose anger is the cause of earthquakes. The Kashima deity suppresses this dragon king, whose head and tail are twisted and overlap at one point. Because the Foundation Stone is located above this point, no matter how violently the dragon king shakes, it will not destroy human society. An old saying goes: “The Foundation Stone will not be thrown off no matter how great the shaking, as long as the Kashima deity is present.” Therefore, I name this record of the earthquake “Foundation Stone.”^[2]

Here yin, yang, and the five phases mix with numerology, the will of deities, popular monsters, and the prestige of a famous Chinese poet to explain earthquakes and reassure readers that the present disaster is a normal yet rare occurrence in the larger picture of a peaceful, well-governed era. Variations on the old saying Ryōi cites about the Foundation Stone and social stability appeared in the literature after every major early modern earthquake. Such invocations of stable foundations served as a reassuring formula.

Notice that although Ryōi cites the five phases of yin and yang as the physical mechanism causing the earth to shake, the intentions and actions of kami (deities) also play a role, albeit one Ryōi does not articulate clearly. Although Ryōi obviously intended to put a positive spin on events, his claim of kami causing a terrifying, deadly event as a way of reporting that good fortune lies ahead hearkens back to a much older notion of kami as capricious, violent, and beyond human control.^[3] Of course, Ryōi's purpose in writing was to sell books, not to achieve rigorous academic consistency. One importance of Foundation Stone for a study such as this one is that it displays many of the possible explanations of earthquakes that had devel-

oped by the middle of the seventeenth century, a time when older and newer theories mixed and a clear consensus had yet to emerge.

As Ryōi's writing indicates, there were many dimensions to the perceived causes of earthquakes. This chapter focuses on scientific thought, broadly defined, with some attention to religious matters, especially cosmology. I argue that with respect to earthquakes and the broader world of ideas, there was no sudden paradigm shift at either end of the early modern era. Periodization based on government institutions does not necessarily correspond with other realms of human endeavor. Buddhist cosmology and other ideas common in the medieval era carried over into the seventeenth century, where they mixed with Chinese-derived cosmology and certain European ideas. Older concepts never entirely faded, but by the eighteenth century a consensus emerged that imbalances in yin and yang energy
were the proximate physical cause of earthquakes. Though the details varied from writer to writer, the most common basic scenario was that yang energy accumulated under the ground and sought to rise. If soil and other conditions impeded its natural propensity to rise, the pressure from this yang energy built up to the point that it exploded. The usual mechanisms posited for yang energy entering the ground, ordinarily the realm of yin, were wind and heat from the sun entering natural openings in the earth.^[4]

I further argue that the Ansei Edo earthquake called this yin-yang view into question, but no obviously better theory was available as a radical replacement. Alternative theories such as the buildup of electrical charges under the earth or the ingredients of gunpowder mixing under the earth closely resembled the mechanism of yin-yang in key respects. The lack of a clearly superior explanation for earthquakes at the start of the Meiji era is one reason that older ideas about earthquakes influenced the modern development of seismology. To contextualize the situation in the early Tokugawa period, I briefly discuss the medieval notions of natural disasters. I take up the situation in the Meiji era and beyond in the final chapter.

• [1] How Ryōi can make this claim is unclear, because at the beginning of Foundation Stone he clearly states that the earthquake began on the first day of the fifth month, and all other sources are in agreement with this date. There was a rich tradition in Japanese and Chinese lore of earthquakes presaging other events—often outbreaks of disease, famine, military problems, and so on. For more details, see Hagiwara Takahiro et al., Kojishin: Rekishi shiryō to katsudansō kara saguru (Tōkyō daigaku shuppankai, 1982), 45–46; Unno Kazutaka, “Kigan, majinai no tsukawareta Nihonzu,” in Unno Kazutaka, Tōyō chirigakushi kenkyū, Nihon hen (Osaka: Seibundō shuppan, 2005), 222, 251 (n. 15); and Hashimoto Manpei Jishingaku kotohajime: kaitakusha Sekiya Seikei no shōgai (Asahi shinbunsha, 1983), 49–54. Relevant to Ryōi’s use of Su Dongpo’s poem, Hashimoto (p. 50) and Unno explain that in Buddhist-influenced earthquake divination, earthquakes might be caused by the movement of the fire (or hearth) deity, the dragon deity, the golden-winged bird, or the celestial king. Depending on which month or days of the month these types of earthquakes occur, they could portend either good or bad fortune.
• [2] Asai Ryōi, Kaname’ishi (1662), in Taniwaki Masachika, Oka Masahiko, and Inoue Kazuhito, eds., trans., Kanazōshishū (Shōgakkan, 1999), 82–83. For details on the history of Kashima’s Foundation Stone in connection with earthquakes, see Gregory Smits, “Conduits of Power: What the Origins of Japan’s Earthquake Catfish Reveal about Religious Geography,” Japan Review 24 (2012): 41–65.
• [3] Early accounts of kami often described them as inscrutable, allotting curses (tatari) for no discernible reason. Medieval kami, by contrast, usually doled out rewards and punishments in accordance with and as exemplifiers of the norms of human society. See Satō Hiroo, Shinkoku Nihon, Chikuma shinsho 591 (Chikuma shobō, 2006), esp. 67–71.
• [4] This basic concept derives from Chinese thought and closely resembles Aristotelian notions of earthquake mechanics in which underground pneuma is the substance that causes the earth to shake. As Emanuela Guidoboni and John E. Ebel point out, “In China, as in Europe, the pneumatic theory survived for a long time and was extraordinarily popular for almost two thousand years, becoming the most enduring and widespread theory that has ever been developed.” Guidoboni and Ebel, Earthquakes and Tsunamis in the Past: A Guide to Techniques in Historical Seismology (New York: Cambridge University Press, 2009), 152.