Disasters, Vulnerability, and time
Whether seismic waves caused by the rupturing of faults cause a disaster in any particular case depends on many circumstances beyond the obvious question of the quantity of energy released (magnitude). As Christof Mauch points out, “The shifting of tectonic plates, for instance, may not be absolutely predictable, but from a geological point of view it is 'normal.' The vast majority of these shifts go unnoticed, and no geologist would think of labeling them as a catastrophe. In other cases, nature may supply the trigger for a disaster, but whether we call a natural occurrence a catastrophe depends largely on our perception of its impact on humans.”
Nature produces a variety of hazards or potential hazards. When these hazards interact with human society, they might lead to a “natural disaster” or catastrophe, depending on that society's level of vulnerability. Vulnerability is a function of many variables. Consider one aspect of location, for example. Estimates are that a magnitude (M) 7.5 earthquake in Los Angeles would produce roughly fifty thousand victims, but this figure would increase to one million should an earthquake of the same magnitude strike Teheran. The differing vulnerabilities of Los Angeles and Teheran are the result of multiple factors, the most important of which is the quality of building and infrastructure construction. Vulnerability is also a variable within a given society. Indeed, the emphasis on studies of disasters since the 1980s has been to focus on factors such as social class, poverty, or other attributes of certain social groups that result in greater vulnerability for them. The limited English-language literature dealing with the Ansei Edo earthquake has assumed that Edo's less affluent residents were more vulnerable in this event. We will see, however, that in many respects this assumption is inaccurate.
Major factors contributing to a society's vulnerability to natural hazards include location, infrastructure, sociopolitical structure, economic circumstances, technology, religion, and ideology. All of these factors develop and persist over time. In other words, time is a fundamental question in the context of vulnerability. As Anthony Oliver-Smith explains, “The life
history of a disaster begins prior to the appearance of a specific eventfocused agent. Indeed, in certain circumstances disasters become part of the profile of any human system at its first organizational moment in a relatively fixed location or area.” In light of this insight, when did the Ansei Edo earthquake begin? Moreover, when did it end?
There is, of course, no “correct” answer to these questions, and one can usually push historical beginnings ever further back in time. Assuming roughly half a century for Tokugawa Japan's institutions and society to mature, and focusing on the context of major earthquakes and the emergence of typical patterns of response to them, I would propose 1662, the year of the Kanbun earthquake, as a plausible starting point. In other words, Ansei Edo was in many respects the culmination of trends that first emerged in 1662. As for the end, although Edo was largely rebuilt by roughly 1858, the Ansei Edo earthquake remained a part of popular memory and influenced understandings of earthquakes well into the twentieth century. Indeed, as I argue in this book, its legacy persists to the present. The 1995 Hanshin-Awaji (Kobe) earthquake resulted in a revival of academic interest in the Ansei Edo earthquake and in claims that a variety of precursors preceded the Kobe event—the same types of claims made in 1855 and 1856. Likewise, as we have seen, the Great East Japan Earthquake and tsunami of 2011 revived interest in earthquake lore and approaches to earthquakes that emerged in 1855. It is in this sense that I refer to the Ansei Edo earthquake as having a long history and continuing legacy. Because I examine Ansei Edo and its influence in the context of major earthquakes of the early modern and modern eras, some basic information about these seismic events is necessary at the start.
-  Christof Mauch, “Introduction,” in Christof Mauch and Christian Pfister, eds., Natural Disasters, Cultural Responses: Case Studies toward a Global Environmental History (New York: Lexington Books, 2009), 4.
-  Mauch, “Introduction,” 9.
-  Anthony Oliver-Smith, “Theorizing Disasters: Nature, Power, and Culture,” in Susanna Hoffman and Anthony Oliver-Smith, eds., Catastrophe and Culture: The Anthropology of Disaster (Santa Fe: School of American Research Press, 2002), 27–28.
-  Ibid., 30.
-  Perhaps the most influential such work was Wadatsumi Kiyoshi, Zenchō shōgen 1519: Hanshin-Awaji daishinsai 1995 nen 1 gatsu 17 nichi gozen 5 ji 46 fun (Tōkyō shuppan, 1996).