Postscript: Rhetoric after the Great East Japan Earthquake

Any systematic discussion of an event as large as the March 11, 2011, Great East Japan Earthquake, tsunami, and nuclear disaster is well beyond the scope of this study. Indeed, sorting through the data and assessing the larger significance of this event will be an ongoing project for years to come. From this study, it should be clear that the Sanriku coast of northeastern Japan has been no stranger to large earthquakes and deadly seismic sea waves. Indeed, the 1896 tsunami still holds the dubious distinction of being the most deadly tsunami in Japan's history. The subduction zone off the Sanriku coast was a well-known “earthquake nest,” at least among seismologists. Had an earthquake of M7 or M8 occurred at the same place and the same time, it would still have been deadly and destructive, but the event would have been within the pale of expert imagination. The occurrence of an M9-class earthquake took many, but not all, experts by surprise. Moreover, because much of the seismological community, politicians, and the public have been fixated for decades on the possibility of a repeat of the 1854 Ansei Tōkai/Nankai earthquakes and tsunamis, the 3/11 disaster was even more of a surprise. The nuclear disaster accompanying this event added a new dimension of apprehension to the massive death and destruction caused by the wave trains, which reached nearly forty meters in some places. Indeed, for these reasons, it may even be reasonable to call this multifaceted disaster “unprecedented,” at least in terms of its effects.

The element of surprise became the major defense of TEPCO officials and politicians. It was “an act of God” (kamisama no shiwaza), said acting finance minister Yosano Kaoru in May 2011. Others offered similar explanations for their lack of preparedness, characterizing the event as “beyond anything we could have supposed” (sōteigai). In a scathing critique of such excuses, seismologist Robert Geller characterizes the nuclear disaster as an act not of God but of “negligence” or “omission.” Megathrust earthquakes in Kamchatka (1952, M9.0), Alaska (1964, M9.2), Chile (1960, M9.5), and Sumatra (2004, M9.3) should have prompted some consideration of the possibility of such an event occurring in one of Japan's subduction zones. Furthermore, an M9-class earthquake in the Cascadia Subduction Zone probably generated the “orphan tsunami” of 1700, and the Jōgan earthquake of 869 that struck Japan's Sanriku coast was probably an M9-class event, described in the Journal of Geology in 1991 and other publications in subsequent years. Moreover, several experts in the years before the 3/11 disaster specifically warned of an M9-class earthquake and tsunami causing disastrous consequences for nuclear plants. Policy makers and power company officials ignored them.[1]

The public discourse on 3/11 is still evolving, although some aspects of it are clear. Here I briefly examine rhetoric in the wake of 3/11 in light of the early modern post-earthquake rhetoric we have examined. Not only did every major Tokugawa-era earthquake generate private and public materials that characterized the event as “unprecedented,” this term also appeared frequently in connection with modern earthquakes and tsunamis in 1891, 1896, 1923, and 1933. In some respects, the rush by those potentially responsible for the human aspects of the disaster to declare the event outside the bounds of the imagination resembles the earlier declarations of earthquakes as unprecedented, albeit with much more self-interest at stake. Rebukes pointing out that TEPCO and nuclear regulatory authorities should indeed have been able to imagine an M9 earthquake inevitably invoke the seismic past of Japan and surrounding areas.

Characterizing 3/11 as unprecedented would not work well in our information-rich age. Anyone willing to do a modicum of work with a search engine would come to know about the large tsunamis that washed over the Sanriku coast in 1611, 1857, 1896, and 1933. Moreover, by the time of 3/11, the Jōgan earthquake had become widely discussed as a likely M9-class event, and the other M9 earthquakes around the Pacific had been known since the advent of moment magnitude in the late 1970s. If characterizing 3/11 as unprecedented would be implausible, perhaps it could still be regarded as beyond the reasonable limits of the imagination. The discipline of paleoseismology provided the needed term.

Within months after 3/11, paleoseismologists announced the discovery of evidence of an M9-class event in northeast Japan during the Yayoi period (roughly 300 BCE–300 CE) and then evidence of a series of such events averaging out to roughly one-thousand-year intervals of occurrence.[2] This idea of a thousand-year interval, which originated in paleoseismology, soon become part of popular discourse. In the process, it lost a substantial part of its original meaning. The current term is “1,000-year earthquake” (sennen jishin), which functions much like “unprecedented” did in earlier earthquake discourse. Just as “unprecedented” was often a figure of speech to emphasize the sense of enormity of the seismic event in question, so too has the term “1,000-year earthquake” quickly taken on flexible meanings. For example, the main title of a recent book discussing a variety of early modern and modern earthquakes is called Sennen shinsai (1,000-year shaking disaster), a slight variant on this recently popular term.[3] In other words, any large earthquake in the past might now be called a “1,000-year earthquake,” at least in nontechnical contexts.

Insofar as M9-class earthquakes affecting northeast Japan may indeed average roughly one thousand years, emphasizing this point surely shifts focus away from the human contribution to the catastrophe. After all, who could have realistically anticipated an event occurring so rarely? Such a focus helps obscure the fact that an M8-class event on the scale of 1896 or 1933 would have caused vast damage and loss of life, albeit not to the full extent of what occurred in 2011. Moreover, as we have seen, if we take the Pacific region as a whole as our geographical focus, several M9-class earthquakes have occurred in recent decades, some close to Japan. One final point is that even if a thousand years does prove to be the average interval of M9-class earthquakes in northeastern Japan, it does not necessarily mean that another such event will wait for another thousand years. Sudden, violent movements of the earth are notoriously unpredictable, as we have seen throughout this study.

  • [1] Geller, Jishin yochi, 24–66.
  • [2] The coverage of this matter in the newspapers has been extensive. For example, see “Higashi Nihon dai-shinsai: Kyodai tsunami rokusen-nen de rokkai, chisō ni konseki,” in Mainichi shinbun, August 21, 2011, and “Q: Sen-nen ni ichido no kyodaijishin to iwareru Higashi Nihon daishinsai, naze sen-nen ni icihido na no? A: Jōgan jishin no sairai toiu mikata,” in Yomiuri Online, October 20, 2011. See also Dengler and Smits (introduction), “The Past Matters,” for some discussion of paleoseismology.
  • [3] Tsuji, Sennen shinsai.
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